DOI: 10.31038/GEMS.2023542

Abstract

The formation of a new fluid inclusion type in beryl is shown. Primarily the inclusion was composed of water-rich stishovite, which was transported from the lower mantle into the upper crust crystallization level via a supercritical fluid or melt. After trapping and phase change, the primary homogeneous inclusion split due to drastic density changes into two parts by the high beryl solubility under such conditions.

Keywords

New inclusion type, Beryl, Supercritical fluid, Stishovite, Cristobalite, Raman spectroscopy

Method

All microscopic and Raman spectrometric studies are performed with a petrographic polarization microscope with a rotating stage coupled with the RamMics R532 Raman spectrometer working in the spectral range of 0-4000 cm^-1 using a 50 mW single mode 532nm laser. Details are given in Thomas et al. 2022 [1,2]. Note here that the low-frequency portion of the Raman spectrum is, according to Tuschel (2019) [3], the most efficacious for characterizing, differentiating, and screening polymorphs (here SiC) by Raman spectroscopy. Furthermore, the polarization/orientation (P/O) micro-Raman spectroscopy is complementary to micro-X-ray diffraction. According to Tuschel (2012) [4], this method should be used when X-ray analysis is not practical or possible (micro-needles and mineral globules depth in the sample volume).

Sample

The beryl-quartz sample material comes from the Sauberg mine near Ehrenfriedersdorf in the Erzgebirge region/Germany. Details are given in Thomas (2023) [5]. Noteworthy is that the synchronously grown moissanite whiskers in beryl characterize the beryl-quartz paragenesis.

Results

During the study of moissanite [SiC] whiskers simultaneously grown in a small beryl-quartz vein related to the Variscan tin deposit, Ehrenfriedersdorf/Erzgebirge, Germany, the author Thomas [5] found a new fluid inclusion type in beryl formed by a necking-of process [6]. That means both inclusions shown in Figure 1 formed from a primarily homogeneous phase, probably stishovite, trapped during the crystal growth of beryl. The density of both minerals, stishovite and cristobalite, is 4.35 vs. 2.20 g/cm³, respectively [7]. It is well known that stishovite formed at the lower crust would never be preserved over geological time at low pressure and temperature [8]. From earlier studies, Thomas and Klemm, 1997 [9] and Thomas et al. 2022 [1,2] follow a trapping temperature of 720°C at a pressure of ≤2 kbar. During cooling, the initially homogeneous inclusion separated itself into two parts by strong density contrast as a result of cooling. The upper inclusion consists of pure methane with a small cristobalite (Crs) crystal, and the lower inclusion is composed of about 65% cristobalite, 17.4% CH₄, and 17.6% H₂O. The solubility of beryl is at or near supercritical conditions extremely high [1,2].

Figure 1: Two supercritical inclusions in beryl (Brl). CH4 – methane, Fl – aqueous liquids phase. Cristobalite (Crs) in both inclusions gives in the Raman spectrum strong lines at 112.6, 229.8. 418.6, and 1072.1 cm^-1, respectively. The numbers 1 to 7 in the lower inclusions show the points at which cristobalite was determined with Raman spectrometry.

The vapor phase consists exclusively of methane (CH₄), and cristobalite (Crs) forms the solid phase of both inclusions. Cristobalite in the methane inclusion is stable under laser light and is metastable in the water-bearing fluid inclusion (creating quartz). With the used Raman spectrometer, in no case hydrogen using the pure rotational lines S₀ (354.8 cm^-1), S₁ (587.4 cm^-1), S₂ (815.0 cm^-1), and S₃ (1024.9 cm^-1) could be determined – see Petrov et al. 2018 [10]. Also, CO₂ could not be determined. The fluid phase is almost pure water. Alkali carbonates are missing. The cristobalite was primarily water-rich stishovite or coesite, giving the supercritical fluid a minimum pressure of 7 GPa. However, if we accept the water content in the lower inclusion primary solved in the primary stishovite, according to Lin et al. (2022) [11], a pressure of about 30 GPa or more is possible (see also Thomas et al. 2022) [1,2]. Figure 2 shows a Raman spectrum of the cristobalite in the CH₄-rich inclusion of Figure 1.

Figure 2: Raman spectrum of cristobalite, nanodiamond, and carbon in the CH4-rich inclusion of Figure 1. The Raman bands at 109.8, 228, 414.3,792, and 1070.5 cm^-1 correspond to cristobalite. The 1328.5 and 1590 cm^-1 bands correspond to nanodiamonds and carbon, respectively.

The strong and stable nanodiamond band at 1328 cm^-1 and the strong carbon band at 1590 cm^-1 are conspicuous and demonstrate that at the origin of the supercritical fluid, its pressure is significantly higher than the pressure at the place of beryl crystallization. Figure 3 shows the Raman spectra of cristobalite (points 1-7) in the lower inclusion part. Here both bands corresponding to nanodiamond and carbon are entirely missing.

Figure 3: Raman spectra of the cristobalite at different measuring points 1-7 in Figure 1

Figure 4 shows the Raman band of pure methane in both inclusion parts. According to Vitkin et al. (2020) [12], methane is ¹²CH₄ rich. Pruteanu et al. (2017) [13] have shown that methane and water are entirely miscible at high pressure and temperature. This condensed state at high pressure and temperature and at least the phase separation at lower PT-data dramatically influence the properties of the supercritical fluid or melt.

Figure 4: Both inclusion parts’ Raman methane spectrum (CH₄)

Conclusion

The here-described supercritical fluid inclusion in beryl is a new type resulting from the interaction of a beryllium-bearing supercritical melt or fluid with the already present Variscan tin mineralization. The solubility of Be as bromelite [BeO] in a supercritical melt or fluid at temperatures higher than 700°C is extreme, as Thomas and Davidson (2010) [14] and Thomas et al. (2022) [1,2] demonstrated. The extreme physicochemical conditions (at a highly activated state) during the beryl crystallization from a supercritical melt or solution favored the simultaneous crystallization of moissanite [SiC] with beryl [5]. The formation of the new inclusion type shows different scenarios for the origin of beryl and simultaneously grown moissanite: ultrahigh-pressure and high-temperature conditions (1000°C and ~30 GPa) generated in the lower mantle region and low-pressure and low-temperature conditions in the upper crust (720°C, ≤2 kbar). Furthermore, the short study shows that supercritical fluids or melts are highly complex in composition and change permanently on the path between the lower mantle and upper crust. Therefore many reactions are far away from any equilibrium. Further studies are necessary to illuminate these complex processes in more detail. One point is essential: which mechanism is responsible for the extreme enrichment of, for example, beryllium? Are near beryl’s crystallization at supercritical conditions a quantum physical entanglement of Be atoms?

References

1. Thomas R, Davidson P, Rericha A, Recknagel U (2022) Discovery of stishovite in the prismatine-bearing granulite from Waldheim, Germany: A possible role of supercritical fluids of ultrahigh-pressure origin. Geosciences 12: 1-13.
2. Thomas R, Davidson P, Rericha A, Voznyak DK (2022) Water-rich melt inclusions as “frozen” samples of the supercritical state in granites and pegmatites reveal extreme element enrichment resulting under non-equilibrium conditions. Min. J. (Ukraine), 44, 3-15.
3. Tuschel D (2019) Raman spectroscopy and polymorphism. Spectroscopy 34: 10-21.
4. Tuschel D (2012) Raman crystallography, in theorie and in practice. Spectroscopy 27: 2-6.
5. Thomas R (2023) Growth of SiC whiskers in Beryl by a natural supercritical VLS process. Aspects in Mining & Mineral Science 11: 1292-1297.
6. Roedder E (1984) Fluid inclusions. Reviews in mineralogy. In: Ribbe PH (ed): Mineralogical Society of America 12: 644.
7. Frondel C (1962) The System of Mineralogy. John Wiley and Sons, INC, New York and London, Vol. III Silicate Minerals, 7^th Edition, 334 p.
8. Hemley RJ, Prewitt CT, Kingma KJ (1994) High-pressure behavior of silica. Reviews in mineralogy 29: 41-81.
9. Thomas R, Klemm W (1997) Microthermometric study of silicate melt inclusion in Variscan granites from SE Germany: Volatile contents and entrapment conditions. Journal of Petrology 38: 1753-1765.
10. Petrov DV, Matrosov II, Sedinkin DO, Zaripov AR (2018) Raman spectra of nitrogen, carbon dioxide, and hydrogen in a methane environment. Optics and Spectroscopy 124: 8-12.
11. Lin Y, Hu Q, Meng Y, Walter M, Mao HK (2020) Evidence for the stability of ultrahydros stishovite in Earth’s lower mantle. PNAS 117: 184-189. [crossref]
12. Vitkin V, Polishchuk A, Chubchenko I, Popov E, Grigorenko K, at al. (2020) Raman laser spectrometer: Application to ¹²C/¹³C isotope identification in CH₄ and CO₂ greenhouse gases. Applied Sciences 10: 1-12.
13. Pruteanu CG, Ackland GJ, Poon WCK, Loveday JS (2017) When immiscible become miscible -Methane in water at high pressures. Science Advances 3: 1-5.
14. Thomas R, Davidson P (2010) Hambergite-rich melt inclusions in morganite crystals from the Muiane pegmatite, Mozambique and some remarks on the paragenesis of hambergite. Miner Petrol 100: 227-239.

DOI: 10.31038/GEMS.2023541

Abstract

The demand and investigation of groundwater are occasionally increased by the ever-increasing population and abrupt climatic changes. Groundwater is currently the most important source of fresh water, and many researchers are attempting to cover all aspects of this resource in order to achieve sustainable development. This scientific and academic research and studies are attempting to present a multi-range of techniques and methods focusing on groundwater pollution, potentials, assessment, and prediction. To delineate groundwater potential (GWP) zones in the Lower Omo-Gibe Watershed, Omo-Gibe Basin, Ethiopia, an integrated strategy of remote sensing (RS), geographic information systems (GIS), and multi-criteria decision analysis (MCDA) using analytical hierarchical process (AHP) was used. For this purpose, seven GWP influencing thematic layers comprising lineament density, slope, soil, drainage density, landuse landcover, geology, elevation and rainfall map were used. Scale values for the classes and thematic layers within them were determined using Satty’s AHP and based on expert and literary judgment. The thematic layers have been integrated via their rates using weighted overlay spatial function tool of ArcGIS to provide GWP map. The distribution and extents of different potential groundwater zone are 158.05 km² (21.59%), 35.92 km² (4.91%), 214.77 km² (29.34%), 220.59 km² (30.13%), and 102.72 km² (14.03%) for very good, good, moderate and fair zone respectively. The study’s conclusions can be used to develop a groundwater action plan that will effectively protect the study area’s considerable groundwater resources. With regard to the long-term availability of groundwater, this research will be very beneficial to water management.

Keywords

Lower Omo-Gibe watershed, Omo-Gibe Basin, AHP, GIS, GWP, MCDA

Introduction

Groundwater is a valuable natural resource, and finding the best locations for groundwater recharge, monitoring wells, water supplies, and groundwater quality depends on exploration and wise management of this resource [1]. Given the constantly rising demand for freshwater, groundwater is a crucial freshwater resource for maintaining daily life in urban and suburban areas [2]. The importance of studying groundwater potential zones is based on the quantity, quality, and contamination of groundwater. The main causes of the consistent rise in freshwater demand are population expansion, the need for irrigation in agriculture, and climate change [3]. Groundwater as a substitute supply of fresh water has received serious attention due to the dangers of surface water pollution, rapid climate change, and the likelihood of droughts [4]. In order to keep the ecological balance of the earth system, groundwater is an essential part of the hydrological cycle. By providing freshwater for drinking, agriculture, and industry, it maintains life [5]. Because it is less polluted than surface water sources, which are easily contaminated by human activities like industrial and agricultural operations, groundwater becomes a significant alternative supply of freshwater in areas with a semi-arid temperature and environment [6]. Groundwater potential maps are available in many nations of the world, assisting planners and decision-makers in the development, distribution, and management of groundwater resources [1]. Groundwater accounts for one-third of all freshwater abstractions globally [7]. In many regions of the world where water supplies are limited, groundwater is a crucial natural resource for any economic and social growth [8]. Groundwater supplies are a necessity for all economic activity, both internally and outside. However, a study that combines remote sensing and GIS data can offer a good platform for the converging analysis of massive amounts of data using very advanced cognitive process techniques for groundwater exploration. Nations like Ethiopia are seeing a rise in groundwater demand as a result of the nation’s fast urbanization, population growth, and economic development. In the area under examination, groundwater is the most often used resource for agriculture, animal husbandry, and the provision of drinking water. The Lower Omo-Gibe watershed groundwater potential zone mapping will have a significant impact on the sub-basin. Since the Lower Omo-Gibe watershed is the main source of the Omo River, mapping the underground water would improve the nation’s groundwater resources’ sustainable management. Because of this, the current study is interested in delineating the groundwater potential zones within the study area using remote sensing and GIS technology. Seven determining elements were taken into consideration for the study: slope, landuse landcover, Lineament density, Geology, Elevation, Soil texture, and Drainage density. In order to ensure sustainable management and growth of the resource, groundwater exploration has recently seen a rise in the usage of remote sensing and geographic information systems (GIS). With the development of technology, more scientists are employing remote sensing (RS) and geographic information systems (GIS) to evaluate a basin’s groundwater supplies [5]. Geophysical technology-based groundwater exploration methods are expensive and time-consuming [9]. Due of these problems, humans have been forced to use a variety of technologies that can help them research vast areas in a brief amount of time while using few resources. These techniques, which include remote sensing and GIS, have been applied to find groundwater potential zones. Exploring the groundwater potential zone in varied geological settings is made simple and rapid with this method [10-13] Several scholars have employed the RS and GIS procedures to designate groundwater potential zones all over the world [14-17]. Utilizing RS and GIS, groundwater resources can be found and explored. Geology, geomorphology, slope, soil type, rainfall, land use/land cover, lineament structures, and drainage criteria are all important factors [18,19]. Geospatial technologies offer quick and affordable ways to evaluate spatial data across a range of geoscience disciplines [20]. For long-term resource management, it is essential to be able to locate the groundwater potential zone. It aids policymakers, decision-makers, and planners in making sure the groundwater resource is safeguarded from influences on both quantity and quality. The analytical hierarchy process (AHP) is one of the approaches to multi-criteria decision-making that is most frequently used [11]. AHP can be used to demarcate groundwater potential zones since it is an easy, quick, dependable, and efficient procedure [12]. When it comes to creating sustainable groundwater policies in this district, planners and policymakers will find this research to be a useful resource.

Materials and Methods

Study Area

The Lower Omo-Gibe River Watershed is about 2345.5 km² in area and is situated in the Omo-Gibe Basin, south Ethiopia. Lower Omo-Gibe Watershed (Figure 1) mainly covers South nation and nationality region and south-west Ethiopia region. Mirab Omo, South Omo and Basketo Zones are included in this watershed. Woredas such as Maji, Salamago, South Ari, Jinka town, Boko Dawula, Hamera, Nyngatom, North Ari and Mele koza. It has a southern boundary that is formed by the contained river basin that empties into Kenya’s Lake Turkana. The Lower Omo-Gibe watershed plain is distinguished by the fact that, although being rather flat, it has various beach ridges and depressions. It was formed very recently by the subsequent movements of Lake Turkana. The Omo delta, in the south of the Basin and at the northern end of Lake Turkana has aggraded to such an extent in recent years only some 25 km² of the lake is in Ethiopia.

Figure 1: Location map of the study area

Methods and Data Analysis

The groundwater potential in this study was assessed using seven criteria including soil, lineament density, landuse landcover, slope, drainage density, rainfall, geology, For each criteria, thematic maps were created and utilized to assess the groundwater potential of the study area. In this study, the relationship between the variables that were utilized to forecast groundwater potential during weight calculation and the actual groundwater potential was analyzed.

Slope

In mapping groundwater potential, slope is a key factor [21]. It determines surface runoff and vertical percolation of water; hence, it affects groundwater recharge processes [22]. Slope was inversely related to infiltration [23]. Shuttle Radar Topography Missions (SRTM) 30 m resolution digital elevation model (DEM) was used to generate slope map. The slope map was classified into five classes (Figure 2) based on FAO classification standard (Sheng, 1990).

Figure 2: Slope map

Drainage Density

Drainage density has an impact on both the availability and pollution of groundwater. Lithology has an impact on the drainage system, which is a crucial gauge of infiltration rate. Drainage density has an inverse relationship with permeability [3]. As a result, it is a crucial component in determining the groundwater potential zone obtained from DEM data.  Finding the length of the stream and dividing on to the total area of the basin as shown in the equation of Drainage Density DD=L (length/A (area) and using Archydro program [24]. The drainage-density map (Figure 3) was created by dividing themed river maps produced from a basin-wide flow accumulation (Fac) and stream definition operation [25].

Figure 3: Drainage density map

Geology

The geologic environment has a significant influence on the existence and distribution of groundwater in any terrain [26]. One of the most crucial factors in evaluating groundwater potential zones is geomorphology, which relates to an area’s landform and terrain. It gives information on how different landform traits are distributed as well as information on numerous processes, including temperature changes, geochemical reactions, water flow, freezing and thawing, and more [27]. Geologic and Geomorphological maps created by translating length and measurement into kilometers (km), digitizing with the Arc GIS spatial analyzer application, and then saving the data as shape files. The geological structures were modified to raster file format with the corresponding presentation, and the region’s geological state was assessed. The following formula was used to compute the lineament (fault) density (LL) [28]. The geology of Lower-Omo Gibe watershed (Figure 4) characterized by tertiary extrusive and intrusive rock, tertiary, quaternary and Permian-Carboniferous.

Figure 4: Geology map

Elevation

Elevation of the catchment ranges from 333 to 3277 m above sea level (Figure 5). High elevation was found in west and north edge of the study area and decrease toward east and south of the study area except topographically irregular and hilly areas. A higher weight is given for lower elevated zones and lower weight was assigned for highly elevated areas.

Figure 5: Elevation map

Landuse Landcover

One of the key determining criteria to pinpoint areas with potential for groundwater recharge is the landuse and landcover map [29]. Landuse and landcover have an impact on hydrological processes such evapotranspiration, surface runoff, and infiltration. Areas with vegetation cover have high groundwater potential than built-up areas that inhibits the infiltration of water into the subsurface [30]. From land use classes, built-up area has the lowest weight compared to other classes and crop land has the highest weight [31]. Landuse landcover offers essential details on infiltration, moisture, groundwater, and surface water in addition to suggestions on groundwater requirements.  The primary coverings of the land surface by human activity or vegetation are referred to as landuse and landcover, respectively (natural or planted). The land-use type in the study area in accordance with the order of infiltration includes barren land, built up land, crop land, grass land, lichen mosses, open water, shrubs cover area, tress cover area and vegetation aquatic (Figure 6). The landuse landcover layer was obtained from the Ethiopia Sentinel2 LULC 2022. The boundaries in the layer were then visually evaluated using Landsat8 satellite images. Next, the land-use classes changed to the USGS standard classifications. Finally, the layer was entered into the GIS model after the necessary edits.

Figure 6: Landuse landcover

Lineament Density

Lineaments are tectonic-derived linear, rectilinear, and curvilinear features that are visible in satellite photography. These lineaments typically display linearity and curvilinerities in vegetation, drainage, drainage patterns, soil tonality, relief, and tonality in soil in satellite data [32]. In particular, in the lineaments that are not filled by soil, the lineaments may operate as a channel for water to seep into the earth and migrate through the aquifer system due to linear features including fault, fractures, and geological connections between various lithologies. Since it is assumed that the rate of water infiltration increases with increasing lineament density, the lineament density (Figure 7) of a region might indirectly indicate the groundwater potential [33]. These lineaments are mapped with the help of satellite data and can be correlated with faults, fractures, joints, bedding planes and geological contacts which are useful for the groundwater potential study [34].

Figure 7: Lineament density map

Soil

The type of soil texture present in an area has a great impact on the availability of groundwater. Highly porous soils allow easy percolation and infiltration of surface water into the subsurface, and this is ideal for a favourable groundwater potential. Soil properties influence the relationship between runoff and infiltration rates, which in turn control the degree of permeability [35]. Soil texture raster data of the Lower Omo-Gibe Watershed was obtained by HWSD (harmonized world soil database) Version 1.2 at 900 m resolution. Lower Omo-Gibe Watershed consists of five major soil textural groups (Figure 8), such as Eutric Nitosols, Eutric Cambisols, Calcaric Fluvisols, Chromic Vertisols and Haplic Yermosols. Due to their difference in infiltration and porosity, weight of soil texture is assigned on the basis of their infiltration rate.

Figure 8: Soil map

Rainfall

The slope gradient and rainfall distribution have a direct impact on the infiltration rate and the potential for groundwater potential zones [22]. As indicated in Figure 9, the annual rainfall was categorized into five classes: very high (1410-1520 mm), high (1300-1400 mm), moderate (1180-1290 mm), low (1070-1170 mm), very low (946-1060 mm) and extremely very low (831-945 mm). Rainfall generally decreases from east to west and similar to elevation, with annual rainfall varying between 831 mm and 1520 mm.

Figure 9: Annual rainfall map

GIS Based AHP Method

GIS Geographic Information System

A software and hardware combination is a created instrument that has been extensively employed in groundwater potential zones and assessment. A method for limiting the number of target regions for hydrogeo-physical study is provided by the combined RS and GIS analysis [36]. Following site appraisal and selection for sustainable groundwater management, site-specific ground geophysical methods like vertical electrical sounding (VES) and very low frequency electromagnetic (VLF-EM) profiling may be used. In the GIS and RS spatial analysis and modeling, thematic layers for soil, lineament density, drainage density, geomorphology, slope, and LULC are integrated. In terms of groundwater prospect, weights ranging from 1 to 4 were allocated to the classes in order of increasing.

AHP Analytical Hierarchy Process

Developing an Analytical Hierarchy Process (AHP) Model

Making a decision hierarchy is the first step in an AHP analysis. AHP divides the issue into a hierarchy. As adopted by [37] first level of the hierarchy is the goal of groundwater potential zone identification. The second level in the hierarchy indicates the parameters that used to decide the potential zone and the third level is about an alternative to select groundwater potential zone as very good, good, moderate and fair. The benefit of AHP is that it simplifies issue solving by better understanding how to break down challenges. To make sure that all requirements and potential alternatives were followed, it is also feasible to request the participation of specialists [37,38].

It’s one of the techniques employed the most in MCDA approaches, as was indicated in the introduction, this concept has been developed by [39]. The AHP evaluates a collection of evaluation criteria as well as a set of alternate options before selecting the best one with the most weight [40]. It is a strategy for assessing the relative weights of the criteria, different optimization strategies for each parameter, and generating an average rating of the variations that were generated using the predetermined criteria (selection criteria identification) at a certain stage [2]. The AHP is frequently used to establish priorities utilizing expert recommendations and evaluations, reduce issue confusion and complexity, and facilitate decision-making. There should be at least two criteria and two substitutes in every study that has been examined by AHP in order to determine each factor’s weight [41]. Since these criteria were given varying degrees of importance, education and expertise are particularly important for thorough evaluation and analysis. It’s possible to employ both qualitative and quantitative criteria [42]. After using AHP within the MCDA, a decision matrix was produced in each study that was reviewed. Field experiences and literature reviews were used to weigh several parameters on a flexible scale from 1 to 5. Then using a few formulae to get the system’s normalized weight and consistency ratio (CR) (Figure 10) [38].

Figure 10: Methodology flow chart for the present study

Figure 11: Groundwater potential map

Result and Discussion

Landuse Landcover

Land use map of the study area (Figure 6) consists of several classes, viz., Bare area 112 km², Built up area 143 km², Cropland 435 km², Grassland 268.5 km², Lichen mosses 112 km², Open water 97 km², Shrubs cover areas 289 km², Tree cover areas 667 km² and Vegetation aquatic 222 km² as shown in Figure 6 and Table 1. Land use is one of the important criteria for identifying groundwater potential zones. Suitable weights were given to each class and their areal extents were calculated using “Zonal Statistics” in GIS (Table 1).

Table 1: Area covered under different range of parameter of Landuse landcover

Geology

Geology is also one of the input parameter factors in delineating the groundwater potential zones. Four different lithologies have been observed in the study area (Figure 4). Their areal extent has been determined using “Zonal Statistics” in geographic information system domain (Table 2). Geology of Lower Omo-Gibe watershed is dominated by tertiary extrusive and intrusive rock 758 (32.32%), tertiary (397 km², 16.93%), quaternary (845 km², 36.03%) and Permian-Carboniferous (345.5 km², 14.73%).

Table 2: Area covered under different range of parameter of Geology

Slope

The slope of the study area has been estimated from Digital Elevation Model (DEM) data as shown in Figure 2 and Table 3. Flat or gentle slope is suitable for increasing the infiltration amount from rainfall. Otherwise, in steep slope area where the infiltration capacity is very minimum whereas runoff is maximum. From the analysis, slope ranges from 0-5 percent rise covers high area coverage which is 31.29% (734 km²), 5-10 slope categories covers 17.67% (414.5 km²), 10-15 slope  categories covers 13.69% (321 km²), 15-20 slope categories covers 9.46% (222 km²) and >20 slope categories covers 27.88% (654 km²).

Table 3: Area covered under different range of parameter of Slope

Soil Type

Soil type is also one of the most determinant factors in estimating the groundwater. Ten different soil types have been observed in the study area (Figure 8). Their areal extent has been determined using “Zonal Statistics” in geographic information system domain (Table 4). Soil type of Bahir dar zuria is dominated by vertisoil with an aerial extent of 1045.19 km² (67.78%), followed by luvisoil (284.31 km², 18.08%), and other units together cover in the study area as indicated in Figure 8 and Table 4. Based on the hydraulic properties of the soil, the soil classes were accordingly ranked using AHP.

Table 4: Area covered under different range of parameter of soil type

Lineament Density

Lineaments are the natural linear feature like faults, joints and fractures, which can visualize and interpreted directly from remotely sensed data. As shown in the Table 5, lineament density class ranked as very low, low, medium, high and very high with the areal extent of 0-0.83 Km/km², 0.84-1.66 Km/km², 1.67-2.35 Km/km², 2.36-2.93 Km/km² and 2.94-3.77 Km/km² respectively. The total area falling in different range of lineament density is given in Figure 7 and Table 5 which show that most part of the study area have very low lineament density. So very low lineament density indicates very low infiltration rate, whereas the high lineament density areas indicate high infiltration (Table 5) thus a potential zone for groundwater development.

Table 5: Area covered under different range of parameter of Lineament

Drainage Density

Drainage density is a significant parameter for evaluating the groundwater potential zones. The areas having high drainage density have less potential for groundwater recharge, and the areas with low drainage density have a high potential for groundwater recharge. Hence, the areas having low drainage density are favorable for high groundwater potentiality. So, higher weights were assigned to the areas having low drainage density. The drainage density was classified into five categories viz. very low (0.08-091 km/km²), low (0.92-1.67 km/km²), moderate (1.68-2.74 km/km²), high (2.75-3.43 km/km²) and very high (3.44-4.22 km/km²). The highest area was under low density with 225.5 km², followed by very low with 388 km², moderate 510 km², high 589 km², and very high 633 km² as shown in Figure 3 and Table 6.

Table 6: Area covered under different range of parameter of Slope

Rainfall

Rainfall is one of the most important sources of groundwater recharge through percolation in the groundwater system. The average annual rainfall in the study area is grouped into six classes namely extremely very low (831-945 mm), very low (946-1060 mm), low (1070-1170 mm), moderate (1180-1290 mm), high (1300-1400 mm) and very high (1410-1520 mm), covering the area of about 410 km² (17.48%), 370 km² (15.77%), 366 km² (15.60%), 433 km² (18.46%), 376.5 km² (16.05%) and 390 km² (16.63%), respectively as shown in Figure 9 and Table 7. Rainfall distribution along with the slope gradient directly affects the infiltration rate of runoff water hence, increases the possibility of groundwater potential zones.

Table 7: Area covered under different range of parameter of Rainfall

Derived Priorities (Weights) for the Parameters

The AHP method was applied in the current work to determine the weight for each data layer. One of the most widely used techniques for determining the weights of criterion in the Multi-Criteria Decision Making is AHP (MCDM) [38]. To identify the purpose, criteria, and relationship between them, the hierarchical structure of the subject being studied is created as the first stage in the AHP approach. Initially, the AHP approach involved conducting a pairwise comparison of the alternatives using specially created questions that followed the format of the standard AHP questionnaires. In this study, opinions from a range of experts were gathered regarding the potential for groundwater, including hydrologists, hydrogeologists, environmentalists, and GIS experts. The overall method is as described in the following Figure 9. The result of AHP shows that geology has the highest weight (38.39%) followed by slope, which accounts for 23.27%, drainage density 14.54%,  landuse landcover 11.40%, lineament density 7.04% and soil 5.35% of the weight given to each parameter (Tables 1 and 2). When the judgements matrix is consistent and the computed weight has been normalized by multiplying the derived weight of all parameters by 100%, it is then possible to rank the features of each parameter for the purpose of a weighted overlay. Features of each thematic layer were ranked on the basis of influence of groundwater potential within each parameter (Table 8) [38,43].

Table 8: Comparison matrix and significance weightage value of the influential factors

Groundwater Potential Zone of the Watershed

To choose the best location for future groundwater development and management, it is crucial to integrate several groundwater regulating variables for discovering possible potential groundwater resources. Using the WLC of the GIS spatial analysis tool, all created thematic maps were integrated based on their weights and rates. The calculations of all the layers went into creating the GWP map. A prospective groundwater zone map was created by weighing the various theme layers and their specific features see Figure 10. The potential groundwater zone of the study area revealed five distinct zones, namely very good, good, moderate and fair. The distribution and extents of different potential groundwater zone are 158.05 km² (21.59%), 35.92 km² (4.91%), 214.77 km² (29.34%), 220.59 km² (30.13%), and 102.72 km² (14.03%) for very good, good, moderate and fair zone respectively see Table 3. Study area have very high to high potential zone in southern, south west and central portion, while the west and eastern portion exhibits medium to low groundwater potentials. The distribution is more or less a reflection of drainage density, lineament, slope, and soil patterns in addition to geomorphic and geological elements, according to analysis of the groundwater potential map (Table 9).

Table 9: Groundwater potential zone

The region appears to have a great potential for irrigation because there are large expanses of irrigable land with fertile soil available. The watershed lower areas get volcanic sediments that are moved from the watershed upper portions due to its geographic location. The area is seen as one where food security is a worry, despite having a lot of potential for irrigation agriculture due to its good soil, irrigable acreage, and high capacity for groundwater. I consequently suggest that concerted activities by the district and regional governments are required to improve the living conditions of persons who reside in the catchment. I have found in my study that the watershed may be abundant in water resources, particularly groundwater. Groundwater was found to have a high potential in nearly half of the basin. Despite the aforementioned limitation, I am confident that the results can be used to identify solutions for utilizing the local water resources and resolving the issue that the residents have been experiencing. I advise that a thorough investigation be done to determine the quantity and quality of water that is available in order to determine whether it can be used for the intended purpose. Due to the availability of substantial tracts of irrigable land with fertile soil, the area appears to have a high potential for irrigation. Due to its geographical location, the watershed lower portions receive volcanic sediments that are transferred from the watershed top portions. Despite having a lot of potential for irrigation agriculture due to its good soil, irrigable land, and high capacity for groundwater, the region is considered one of the locations where food security is a concern. In order to better the living conditions of those living in the watershed, I therefore propose that coordinated actions by the district and regional governments are needed.

Conclusion

In this study, groundwater potential zone evaluation using remote sensing, GIS, and MCDM methodologies has been successfully used and proven. The generation of thematic layers, the application of AHP to get the weights, and overlay analysis to determine the groundwater potential zone are the three steps of the process. Thematic layers were created by digitizing existing maps using a GIS and remotely sensed satellite image data. Utilizing the AHP, utility weights for the substitutes were provided. The identification of the groundwater potential zone uses an overlay analysis of multiple thematic maps and weighting. Based on remote sensing, GIS, and MCDA methodologies, four categories of groundwater potential zones have been identified in this study region. This particular study deals with the assessment of groundwater potential zones (GWPZs) using geographical information systems and remote sensing techniques in the Lower Omo-Gibe watershed, Omo-Gibe Basin, Ethiopia. The thematic layers influencing GWPZs such as geology, landuse landcover, slope, lineament density, drainage density, soil properties (soil texture, soil type), and elevation maps were getting prepared with the available data, i.e., conventional data, satellite image, and assigned individual weights along with their subclass divisions depending on literature and expertise decision. The distribution and extents of different potential groundwater zone are 158.05 km² (21.59%), 35.92 km² (4.91%), 214.77 km² (29.34%), 220.59 km² (30.13%), and 102.72 km² (14.03%) for very good, good, moderate and fair zone respectively.

Data Availability

Data used in this research are available upon request.

Conflicts of Interest

The author declares that they have no conflicts of interest or personal relationships that could have influenced the work reported in this paper.

Acknowledgments

The authors acknowledge the Ethiopian Ministry of Water, Irrigation and Energy, and the National Metrological Agency for providing the necessary data which is helpful to accomplish this research work.

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DOI: 10.31038/GEMS.2023534

Abstract

Water and soil resources are the foundation of Agriculture high-quality development. Water and soil loss is a serious natural secondary disaster and affects the redistribution of Water and soil resources and land productivity. Soil and water conservation influence high-quality development. After about one hundred years of efforts, soil and water conservation has developed rapidly, for example in China, the surface runoff and soil loss in soil and water loss areas have decreased rapidly. The people’s living conditions have gradually improved as economy and society development. Now, economy and society development enter a new time, people living level increase and put forward higher requirements for soil and water conservation because the current efficiency of soil and water conservation cannot meet people’s higher requirements. In this paper, a new theory of soil and water conservation developed. The results shows that soil and water losses refer to the process of transferring soil and water resources from one place to another, and the consequences of these losses can be divided into positive and negative effects on high quality development. Soil and water conservation is not only the use of some methods or measures to reduce soil erosion to soil allowable loss requirements, but also to make efficient use of soil and water resources. The construction standard of soil and water conservation measures must be based on the allowable amount of soil erosion and be applied using spatially optimal allocation, and the high-quality sustainable management of soil and water conservation should be made to ensure regional ecological security and realize the high quality and sustainable development of soil and water conservation.

Keywords

Soil and water loss, Soil and water conservation, Food and ecological security, Soil and water conservation measure, Most optimum distribution of resources, Sustainable development

Introduction

Neotectonic movement is tectonic change occurring in the Tertiary and thereafter, and is characterized by vertical and horizontal movement. Under the influence of many natural background factors, such as mountainous terrain and unstable monsoon precipitation, formed by intense neotectonic movement, as well as the long history of agricultural development and the large population, China has become one of the countries with the most serious soil erosion, notably on the Loess Plateau .Water and soil loss affects the carbon and nitrogen cycles of terrestrial ecosystems, vegetation ecosystem products and services, the ecological environment and economic development, and ultimately the quality of life and sustainable development of the public. Over the past 100 years, great progress has been made in the work of soil and water conservation in China with the unremitting efforts of the vast number of soil and water conservation workers. For example, as evidenced by the establishment of the State Key Laboratory of Soil Erosion and Dryland Agriculture in Yangling, China, the concept of cover degree and cover rate of water conservation forest has been developed [1,2]. The degree of vegetation coverage is the percentage of the total area covered by the vertical projection area of the tree canopies, and the vegetation cover rate is the proportion of high-quality grassland or forestland area of the total land area in a region or a country. The vegetation coverage includes the effective cover degree, critical degree, and potential coverage [3,4]. The establishment of a large area of soil and water conservation vegetation has been established in the area of in the area of soil and water loss region, such as water conservation forest (or vegetation), Windproof and sand-fixing forest, water source conservation forest, and adult forest construction standards and their construction scale and suitable developmemt scale have also been established; the effective coverage rate of wind-proof sand forest, of water conservation forest, and of water conservation forest [1-9], the theory of soil water resources utilization limit by plants and the soil moisture vegetation bearing capacity appeared in 2000 [3,4,9,10]. However, due to the lag in theoretical research, construction standards of soil and water conservation measures are low with small range of water conservation measures, the spatial allocation of soil and water conservation measures is unreasonable, the work of soil and water conservation attaches importance to quantity and not quality, and its efficiency is low, which cannot meet the modern needs of high-quality development of soil and water conservation. Such incidents as drought, forest fires, extreme weather and precipitation, hurricanes, and flash floods lead to widespread erosion of soil and water conservation vegetation, collapse of dams and other incidents, resulting in serious soil erosion, destruction of farmland, villages, roads, and vehicles, which affects transportation, food and ecological security, and cause large losses to the state and society. In order to overcome these difficulties, promote the high-quality development of soil and water conservation, and meet current requirements of the public for soil and water conservation, it is necessary to develop a new theory of soil and water conservation. Through comprehensive analysis of relevant literature, a new theory of soil and water conservation is proposed. The purpose of the paper is to better understand the new theory of soil and water conservation and carry out High-quality sustainable development of soil and water conservation. The main content as the followings [11].

Soil and Water Loss

Soil erosion is a natural phenomenon, and it originated in China as a technical term in the early 20th century [12], where it was applied to the Northwestern Loess Plateau [13]. The forces that cause soil and water loss are called external soil and water loss forces, including water, wind, temperature (freeze–thaw) and son on. The term erosion has long been used in geology, mostly to express the flattening due to external force, and soil erosion was first mentioned in the book of Kozmenko in 1909 [12]. It was then widely used and was introduced into China in the 1930s. Soil erosion refers to the whole process of soil and its parent material, as well as the destruction, stripping, transport, and deposition of surface components of the land under external forces such as hydraulic, wind, freeze-thaw, and gravity [12]. Water power is the force produced by the flow of water and wind is the magnitude of the force that air exerts on an object. Temperature is the measure of the average translational kinetic energy of the molecular motion, and is the collective expression of molecular thermal motion. At present, people’s understanding of water and soil loss is not uniform. It has been argued that soil erosion refers to the destruction and loss of soil and water resources and land productivity under the action of external forces, including surface erosion and soil erosion; most believe that water and soil loss is equivalent to soil erosion, i.e., soil erosion by hydraulic, wind, or gravity erosion, resulting in soil dispersion, transport, and accumulation processes. However, we are entering a new period. In order to promote the high-quality development of soil and water conservation in this new period, we should first unify the understanding of water and soil loss. The water and soil loss are the process of soil and water resources transferring from one place to another, which includes both generalized and narrow-sense soil erosion. Generalized water and soil loss refers to the process of carbon and nitrogen cycle, land productivity, and ecological environment change caused by the transfer of soil and water resources induced by external forces. Water and soil loss in the narrow sense is equivalent to soil erosion [14].

Consequences of Soil and Water Loss

The influence of Water and soil loss on high-quality development of soil and water conservation can be divided into positive and negative effects as follows:

Water and Soil Loss Leads to Decline or Even Loss of Soil Fertility and Land Productivity in the Water and Soil Loss Regions

The term soil fertility refer to the capability of soil to support plant production in agricultural contexts [15]. Serious water and soil loss will affect carbon and nitrogen cycles in agriculture ecological systems and result in surface soil thinning of fertile soil in the water and soil loss region, and decreases in cultivated land area, soil fertility, and crop [16].

Soil Erosion Affects People’s Daily Activities

Water and soil loss destroys house, farmland, roads, bridge and silts up rivers, lakes, and reservoirs, which affects People’s Daily activities. Floods, landslides, mudslides, and other serious soil erosion results in siltation of channels, lakes, and reservoirs.

Water and Soil Loss Pollution Water Quality and Affects Ecological Balance

Water and soil loss accelerates non-point source pollution. When heavy rain happens, strong surface runoff will pile up surface garbage into rivers, seriously affecting their water quality and irrigation. A typical example is the poor water quality of the Yangtze River.

Typhoons, Haze, Dust, and Dust Storms Affect People’s Health, Travel, and Social Activities

As the economy and society develops, people are increasingly interested in health, and travel and social activities are becoming more frequent, while typhoons, haze, dust-raising weather, and dust storms affect flights and road traffic, and seriously hinder people’s rapid travel and social activities.

Water and Soil Loss Accelerates the Formation of Unique Landforms and Promotes the Development of Eco-tourism

Soil and rock through hydraulic, wind, freeze/thaw, and joint action of other external forces form a number of magic, wonderful natural landscapes, which raise living standards and accelerate the high-quality sustainable development of eco-tourism. For example, there are some famous eco-tourism sites such as Keshiketeng stone array scenic spots in the northeast of Keshiketeng County, Danxia natural scenic spots in Yulin city, and Zhashui cave in the Qinling Mountains. Zhashui cave is the result of long-term dissolution of groundwater. Calcium carbonate in limestone forms micro-soluble calcium bicarbonate under the action of water and carbon dioxide. Because the limestone layer contains different lime quality with different erosion degrees, it is gradually dissolved and divided into independent, diverse, steep and beautiful peaks, and caves in a strange landscape, which promotes eco-tourism and local economic development. Hukou waterfall was a Hukou waterfall but now has become a tourist hot spot.

Water and Soil Loss Forms Silt Plains and Expands Land Area in Estuaries

A large amount of sediment is deposited in estuary areas, over time forming silt plains and expanding the land area, which increase nitrogen density in soil, soil fertility, land production, and carbon dioxide fixation; for example, Chongming Island at the mouth of the Yangtze River and the Huanghe Delta at the mouth of the Yellow River. Chongming Island was originally only a small sand dune and, as more sand was deposited, the sand dunes grew larger and became an island where fishermen lived.

Soil and water conservation workers should broaden their horizons, make best use of the advantages of water and soil loss and bypass the disadvantages of water and soil loss. Thus, they can meet the requirements of rapid and high quality economic and social development, especially to strengthen the prediction and prevention of serious soil erosion phenomena caused by typhoons and haze caused by strong winds, dust-raising weather, and sandstorms.

Soil and Water Conservation

Soil and water conservation refers to the use of certain measures and technologies to reduce the loss of soil and water to a certain goal, i.e., soil allowable loss, to make efficient use of soil and water resources in the process of water and soil loss and increase the ecological, economic, and social benefits of soil and water resources in the soil and water loss system to provide high quality products and services for social development and to maximize the safety of the life and property [14]. Soil and water conservation makes rational use of soil and water resources to achieve sustainable development. For example, introduction of flood irrigation with high sediment concentration to form high-quality farmland using water sources of rivers, lakes, and reservoirs in the sand area; drawing water by gravity or by machinery; washing sand dunes using hydraulic power, and carrying sand to positions to form high quality farmland, or using runoff and topography to promote eco-tourism, such as the Shapotou and Hukou tourist attractions in the Loess Plateau. Soil and water conservation measures can effectively conserve soil and water [17]. These measures include engineering measures, farming and biological measures for soil and water conservation. In the restoration of vegetation, natural forces can be used to restore vegetation in uninhabited areas; however, in areas where there is a population, artificial interference should be used to restore vegetation in order to create the vegetation ecosystem goods and services to meet the needs of human production and life. Over the past 100 years, with the unremitting efforts of the vast number of soil and water conservation workers, China has made great progress in its work on soil and water conservation. A large area of soil and water conservation vegetation has been established in water and soil loss areas, and a large number of reservoirs have been built; some water and soil conservation measures such as water and soil conservation projects including dams or levees have been set up along the tributaries of the Yellow River and other soil erosion areas, which have made great progress in controlling water and soil loss below the allowable amount and promoting regional economic development. However, due to the lag in theoretical research on soil and water conservation, the construction standard of soil and water conservation measures is low and imperfect, and the spatial allocation of soil and water conservation measures is not balanced. For example, silt storage dams for farmland buildings have played important roles in preventing floods, consolidating the return of farmland to forests or grassland, safeguarding ecological security and food security, and promoting the development of economy and social stability. However, in construction of silt storage dams, the problems of low-quality construction, serious disease-risk dam, and poor management of reconstruction, especially concerning the large number of small dams, have not received enough attention [18]. Therefore, it is urgent to strengthen the study of soil allowable loss on different underlying surfaces, formulate high quality and strict standards for soil and water conservation engineering and vegetation construction, and carry out spatial optimal allocation to obtain maximum soil and water conservation efficiency. The space optimal configuration is expressed by the spatial optimal configuration coefficient. Spatial optimal allocation coefficient indicates that, in a water and soil loss area or watershed, soil and water conservation funds or measures may have different allocation methods; these different allocation methods result in different soil and water conservation efficiency, i.e., different surface runoff and soil loss. The optimal allocation of space is the allocation that results in maximum soil and water conservation efficiency.

High-quality and Sustainable Management of Soil and Water Conservation

In order to achieve high-quality and sustainable development of soil and water conservation, it is necessary to implement high-quality and sustainable management of soil and water conservation measures, reduce or even eliminate unsafe traffic accidents and loss of life and money accidents caused by serious soil and water loss, reduce dam dyke damage and flood dam overturn caused by inadequate design, material fatigue, rodent damage and piping, and continue to achieve the maximum efficiency of soil and water conservation. The high-quality sustainable management approach for soil and water conservation includes: Based on the external forces of soil and water loss, the temporal and spatial changes of soil and water loss, and the requirements of residents, we should improve the anti-erosion standards of infrastructure such as homes, roads, Bridges, levees and DAMS, improve the design and construction standards of soil and water conservation measures, and optimize spatial allocation to avoid soil and water conservation from exacerbating ecological security. At the same time, the prediction of extreme weather such as sandstorm, tornado, heavy rainfall, earthquake and other geological disasters should be strengthened, and Beidou satellite, UAV and other monitoring equipment should be used to dynamically monitor key sites prone to geological disasters. The corresponding emergency plan for high-quality sustainable management of soil and water conservation should be formulated, and the emergency plan should be launched immediately in case of disasters. According to the theory of resource utilization limit and the theory of vegetation carrying capacity, the utilization limit of soil water resources and the vegetation carrying capacity of soil water in water shortage areas should be the limit of soil water resources utilization and the vegetation carrying capacity of soil water, and the high-quality sustainable management of soil and water conservation vegetation should be implemented to continuously obtain the maximum efficiency of soil and water conservation [14] to reduce loss of life and property.

Application Effect

Because of the large area of soil and water loss area, people’s understanding level of soil and water conservation is uneven, and the development of soil and water conservation work is unbalanced. In the areas with early understanding and high level of soil and water conservation, the new theory of soil and water conservation is practiced consciously to achieve high-quality sustainable development of soil and water conservation, and satisfactory results have been achieved. For example, we have been engaged in innovative research on soil and water conservation for many years, and carried out high-quality sustainable management of soil and water conservation vegetation for Caragana （Caragana Korshinskii） shrubland in the Guyuan experimental Station the semi-arid loess Hilly , Guyuan, China according to the theory of utilization limit of soil water resources and the theory of soil water and vegetation carrying capacity. In order to reduce soil water consumption in the dry season, the vegetation cover of Caragana Korshinskii forest should be kept at least 60% to ensure that the canopy coverage is not lower than the construction standard of soil and water conservation forest in the region. In the growing season, when the soil water resources in the soil depth ranged from land surface (0 cm) to maximum infiltration depth (290cm) decreased to the soil water resources utilization limit by plants of 212.7 mm, the plant water relationship entered the critical period of plant water relationship regulation. The end time of plant water relationship regulation is when the plant water relationship regulation period fails.

If plant density of soil and water conservation forest, expressed by goal tree species in the critical period of plant water relationship regulation is greater than soil water vegetation carrying capacity, timely plant water relationship regulation should be carried out according to the soil water vegetation carrying capacity, so as to ensure normal plant growth, prevent drought from leading to early deciduous leaves, dry shoot or death of caragana (Caragana Korshinskii ) before the rainy season, resulting in forest canopy intercession and disappearance, so as to continuously obtain maximum soil and water conservation efficiency. For the economic forest, such as red plum and apricot, firstly enlarge the tree pit and improve the quality of terrace according to local conditions, realize all the precipitation in situ infiltration, and reduce the soil and water loss to the allowable soil loss. At the same time, according to the local weather forecast, green house and high smoking at 1 meter above land surface measures were taken to prevent the damage of low temperature frost during the flowering and young fruit period in the period from late March to early May, and high efficiency cyhalothrin was adopted around May 20 to prevent the harm of eating worms. If the conservation density in the critical period of plant water relationship regulation exceeds the soil water vegetation carrying capacity, the plant water relationship in the critical period of plant water relationship regulation should be regulated first according to the right amount of leaf when the plant density is equal to the soil water vegetation carrying capacity, and then the vegetative growth and reproductive growth relationship should be regulated according to the right leaf amount in the carrying capacity and the leaf amount and quality fruit relationship to obtain the maximum yield and economic benefits, the income of red plum and apricot mu can reach more than 10,000 yuan [14]. Since 2017, the national high-quality red plum apricot demonstration base has been established on hilly land to demonstrate and promote high-quality production methods of red plum and apricot (Figure 1).

Figure 1: solar Power Plant (Dengkou, right photo)

After the founding of New China, Gao Zuyu, the secretary of Gaoxigou Village, Mizhi County, Yulin City, China，under the guidance of Mr. Tao Ke, carried out comprehensive management of soil and water conservation, such as silting dam, terraced fields and forest and grass vegetation construction. After years of continuous efforts, Gaoxigou Village has built a barren mountain gully with broken surface, serious soil and water loss into terraced mountain tops, pine and cypress contiguous pieces, soil loss is lower than the allowable soil loss, and efficient use of water and soil resources. Gaoxigou cultivated organic apples, e-commerce helps to develop ecological tourism, walk a variety of management. In 2020, the per capita income is 18,851 yuan, far exceeding the county’s average level (5,834 yuan), becoming a typical example of high-quality sustainable development of soil and water conservation in the area. The government of Hangjin Qi built diversion sluices, diversion channels, ecological levees, and drainage sluices connected with the main trunk channel to divert water from the Yellow River into the Kubuqi Desert and back water into the Yellow River. More than 200 million cubic meters of water were diverted in total, reducing runoff, sediment and siltation in the middle and lower reaches of the Yellow River, and forming a surface area of nearly 20km² and an ecological wetland of nearly 60km² in the Kubuqi Desert. Plants grow well, some water birds come to roost here, let the desert into an oasis wonder, aroused the attention of all countries, the diversion of water and sand control law let the world imitate.

State Power Investment Group Beijing Electric Power Co., Ltd. innovatively put forward the concept of “photovoltaic sand control and ecological restoration”. The Dengkou Industrial Park Management Committee of Bayannur City, Inner Mongolia cooperated with the State Power Investment to build the Dengkou photovoltaic sand control project. It not only reduces exposure to sunlight under photovoltaic solar panels and near-surface wind speed, promotes plant growth, and achieves good desertification control effect, but also obtains green and clean energy, which achieves good effect, as shown in the Figure. It is currently promoted in Gansu, Ningxia, Tibet, etc. Build wind power stations in tuyere areas to reduce wind and sand hazards [14]. The establishment of high-standard construction and water and soil conservation projects in soil erosion areas can not only avoid the harm of soil erosion, but also achieve good ecological, economic and social benefits, such as high-standard Hani terraces, e Guanyin Ge in Building in Yangzi river, Ezhou, Hubei Province, Dujiangyan and contemporary Three Gorges Dam, which have continuously given full play to the comprehensive benefits of flood control, irrigation, water transportation and social water use for two thousand years [14]. On the contrary, in the areas without the guidance of the new theory of soil and water conservation and the implementation of high-quality sustainable management, once encountered hurricanes, sandstorms and rainstorms, there will be serious dam collapse, dam collapse, flood destroyed houses, roads and farmland, and other serious events affecting high-quality development, resulting in the destruction of civil houses, roads, levees and storage DAMS. Car scrapping, human casualties and other serious events, such as in 2021 in many European countries, the United States and China’s Henan, Shanxi and Shaanxi provinces serious flood disaster. In 2022, severe soil and water events occurred in many parts of China, such as shaanxi, Shanxi and Henan province and Pakistan in 2022.

Acknowledgment

This project was supported by the National Key Research & Development Plan (Project No: 2016YFC0501702) and the National Natural Science Foundation of China (Project Nos: 41271539 and 41071193). We thank International Science Editing (http://www.internationalscienceediting.com) for editing the English language in the manuscript.

Competing Financial Interest Statement

There are no competing financial interests

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