Valley Basin Research Articles

A compendious approach for renewable energy assessment based on satellite and ground truth data: Bilate catchment, Rift Valley Basin, Ethiopia

A compendious approach for renewable energy assessment based on satellite and ground truth data: Bilate catchment, Rift Valley Basin, Ethiopia

Distribution and possible sources of atmospheric microplastic deposition in a valley basin city (Lanzhou, China)

The deposition is an important process of microplastics transporting from atmosphere to water and soil. But the spatial and temporal distribution of microplastics in urban atmospheric deposition and its influencing factors are poorly understood. The current study investigated the possible sources, spatial and temporal distribution, and potential ecological risk of microplastics in deposition from the valley basin of Lanzhou city during the COVID-19 pandemic (from February to August, 2020). The deposition flux of microplastics was 353.83 n m−2 d−1. Most plastic samples were small sized (50～500 µm) and transparent. The dominant chemical composition and shapes were PET, fragments and fibers, respectively. A modified method was conducted to identify the sources of microplastics, and the local sources were suggested as the main possible sources. The distribution of microplastics investigated through the inverse distance weight interpolation showed spatial variation and temporal differentiation which was dominated by the human activity. The rainfall also affected the temporal distribution. The preliminary assessment indicated higher potential ecological risk of microplastics in deposition. This study suggested the dominant effect of human activity on the source and distribution of atmospheric microplastic deposition in city.

Developing a DEM and Elucidating through SWAT to Conserve Soil in Kulfo Watershed of Rift Valley Basin, Ethiopia

Due to uninterrupted erosion and transportation, huge volume of sediments carried away by streams and rivers are finally deposited on the meanders, lakes, and reservoirs when the velocity of the surface water flow decreases. Kulfo River in the southern part of Ethiopia faces a challenge due to massive deposit of sediments. Hydrometeorological and spatial data of Kulfo watershed from the observed stream flow data series near Kulfo bridge and four meteorological station data were used to assess the depositional environment of Kulfo watershed. The data length covers the period from 2000 to 2019. Geomorphic parameters of the watershed were developed by using a 30m × 30m digital elevation model (DEM). The spatial distribution of sediment yield of the study area was estimated using SWAT, the soil and water assessment tool. Scenarios were developed to assess the effectiveness of watershed management interventions provided at the watershed and critical subwatershed level. The model genuinely replicated the observed discharge and sediment with an overall performance of 0.75 as measured by NSE. Twenty-one subbasins were created, and the observed average sediment yield was calculated as 11.9 ton/ha/y. The observed average sediment yield reduction at the hotspot subwatershed level postapplication of contouring, filter strip, terracing, and strip cropping were 40.79%, 57.94%, 66.02%, and 62.93%, respectively. By intricately analyzing, it can be referred that terracing is the best conservation measure to be incorporated into the affected subbasins.

Depth-dependent crustal azimuthal anisotropy in the Salton Trough, southern California

We present new crustal models of azimuthally anisotropic P-wave velocity, isotropic P-wave velocity (Vp), isotropic S-wave velocity (Vs) and Vp/Vs ratio for the Salton Trough. High Vp/Vs ratio is revealed at depths of 2–8 km along the San Andreas Fault, implying the possible presence of fluids. High Vp and high Vp/Vs ratio (>1.8) structures of the mid-lower crust beneath the Salton Trough possibly reflect the underplated gabbroic rocks as a result of the extension-induced partial melting of the upwelling asthenospheric materials. The fast velocity directions (FVDs) generally correlate with the direction of the maximum horizontal compressive stress except that fault-parallel FVDs are found at main fault traces. However, the FVDs in the Salton Trough show complex features. The northern Slaton Trough basin (the northern Salton Sea basin and Coachella Valley basin) is dominated by NW-SE FVDs, which are possibly due to the active compression happening there. E-W oriented FVDs predominate the upper crust of the southern Salton Trough basin (the southern Salton Sea basin and Imperial Valley basin), possibly due to faulting and/or block rotation. As the depth increases (12–18 km), the FVDs to the south of the Salton Sea have an overall rotation and gradually become NW-SE. The depth-dependent variation of anisotropy orientation may be attributed to a large band of underlying heat source that probably causes a change of stress field by imposing thermal stress on overlying rocks. In all, our velocity models suggest that faults in the Salton Trough may bear a high risk of mechanical failures due to the complexities of stress distribution and geological structures as well as the presence of a large volume of fluids and heat.

Eemian to Early Weichselian regional and local vegetation development and sedimentary and geomorphological controls, Amersfoort Basin, The Netherlands

Abstract Two new records from the Amersfoort glacial basin are investigated by means of pollen analysis. The cores are situated in the deeper part, close to the original Eemian stratotype Amersfoort 1 (Zagwijn, 1961) and at the margin of the basin. The aim is to reconstruct the Eemian and Early Weichselian vegetation development and to explore the impact of accommodation space, influx of allochthonous pollen and geomorphology on the vegetation composition. The results of the Amersfoort Basin are compared to the current Eemian stratotype in the Amsterdam Basin and other Eemian sites in the Netherlands. An almost complete Eemian to Early Weichselian sequence (E2-EWII) was retrieved from the deeper part of the Amersfoort basin. The late Saalian (LS) to early Eemian transition is not recorded in the Amersfoort basin, in contrast to the deeper Amsterdam Basin. The basin marginal core Den Treek reveals a condensed late Eemian (E5-6) and Early Weichselian (EW I-II) succession showing the importance of accommodation space. The first impact of the Eemian transgression is registered at the E3 to E4a boundary in the Amersfoort and Amsterdam basins, and highest sea level is proposed at the end of pollen zone E5. Upstream in the Eemian delta, in the palaeo-Vecht valley and IJssel Basin, the transgression is recorded later. The influx of reworked (allochthonous) pollen in clastic sediment units hampers vegetation and climatic reconstructions during the LS and Eemian. The early appearance of Picea in zone E4 and Abies in zone E5 in clastic sediment intervals can be related to long-distance transport by the river Rhine and redistribution in the Eemian delta. Local vegetation development can complicate regional biostratigraphic correlations. Alnus, considered characteristic for the late Eemian (E5-6), shows large differences over short distances in the Amersfoort Basin, related to local alder growth since Eemian E3. Carpinus, diagnostic for pollen zone E5, shows high values in the basins adjacent to higher, well-drained ice-pushed ridges, but low values in low-relief environments. Salt- to brackish-water marshes were present during high sea level in zone E5 in the Amsterdam and Amersfoort basins, while further upstream in the Rhine delta brackish to fresh-water tidal conditions dominated. In line with Zagwijn (1961), the E6 to EWI boundary is defined at the first opening of the vegetation cover with Calluna, Poaceae and Artemisia increase, often coinciding with a lithological change from organic to clastic deposition, reflecting increased landscape instability. The cores from the Amersfoort basin reveal a complete Eemian to Early Weichselian record. It is suggested to define the boundary stratotype for the base of the Weichselian Stage in the Amersfoort Basin. The current stratotype Amsterdam-Terminal reveals a fully developed LS to Eemian transition and contains the boundary stratotype for the base of the Eemian Stage.

Shale gas resources across the world: A future source of energy

Unconventional natural gas resources are very important for ensuring energy security. It is a concern that conventional natural gas resources will be unable to meet growing supply requirements. This concern has prompted a scramble to secure long-term natural gas supplies. In a high oil and gas price environment, unconventional resources are viewed as important and economically attractive components of future natural gas supplies. Shale gas is natural gas produced from shale formations. Gas shales are organic-rich shale formations. Shale gas is a dry gas composed of methane. Various factors which have contributed to its rapid development are mainly advancements in horizontal drilling, hydraulic fracturing, and, perhaps most importantly, the rapid increase in natural gas prices in the last several years as a result of significant variation in supply and demand. India has a high potential for shale reserves. According to the available data, a comprehensive shale gas pilot project carried out in the Damodar Valley Basin has made an initial gasin- place estimate of 300 to 2,100 trillion cubic feet (TCF) in Indian shale gas basins, which is around 300 times higher than the Krishna Godavari Dhirubhai 6 (KG-D6) basin, by far the largest gas field in the country. In this paper, a brief review of shale gas reserves across the world and their government policies has been explained.

A Bi-level Neuro-Fuzzy System Soft Computing for Reservoir Operation

Reservoir operation studies purely based on the storage level, inflow, and release decisions during dry periods only fail to serve the optimal reservoir operation policy design because of the fact that the release decision during this period is highly dependent on wet season water conservation and flood risk management operations. Imperatively, the operation logic in the two seasons are quite different. If the two operations are not sufficiently coordinated, they may produce poor responses to the system dynamics. There are high levels of uncertainties on the model parameters, values and how they are logically operated by human or automated systems. Soft computing methods represent the system as an artificial neural network (ANN) in which the input- output relations take the form of fuzzy numbers, fuzzy arithmetic and fuzzy logic (FL). Neuro-Fuzzy System (NFS) soft computing combine the approaches of FL and ANN for single purpose reservoir operation. Thus, this study proposes a Bi-Level Neuro-Fuzzy System (BL-NFS) soft computing methodology for short and long term operation policies for a newly inaugurated irrigation project in Gidabo Watershed of Main Ethiopian Rift Valley Basin. Keywords: Bankruptcy rule, BL-NFS, Reservoir operation, Sensitivity analysis, Soft computing, Water conservation.

Evaluation of ECMWF's forecasting system for probabilistic urban flood prediction: a case study in Mexico City

Abstract As the world continues urbanizing, including efforts to forge a new framework of urban development is necessary. Recent studies related to flood prediction and mitigation have shown that Ensemble Prediction Systems (EPSs) constitute a valuable and essential tool for an Early Warning System. However, the use of EPS for flood forecasting in urban zones has yet to be understood. This work has the objective to investigate the potential use of the Operational EPS, issued by the European Centre for Medium-Range Weather Forecasts (ECMWF), for probabilistic urban flood prediction. In this research, a precipitation forecast verification was carried out in two study zones: (1) Mexico Valley Basin and (2) Mexico City, where for the latter, forecasts were compared against real-time observed data. The results showed good forecast reliability for a rain threshold of up to 20 mm in 24-hourly accumulations, with the first 36 h of the forecast horizon being the most reliable. The EPS has sufficient resolution and precision for flood prediction in Mexico City, which represents a further step toward developing a flood warning system at the local level based on ensemble forecasts.

Impacts of geometric model simplifications on wave propagation—application to ground motion simulation in the lower Var valley basin (France)

SUMMARYThe numerical simulation of seismic wave propagation in realistic heterogeneous media, as sedimentary basins, is a key element of seismic hazard estimation. Many numerical methods in two dimensions are based on unstructured triangular meshes and explicit time schemes. However, the presence of thin layers and tangential stratigraphic contacts in sedimentary basins entails poorly shaped mesh elements: some triangle heights are extremely small compared to the edge lengths, which requires small time steps in the simulations and thus leads to prohibitive computation times. We compare manual and automatic geological model simplification techniques to modify problematic areas of the domain, so as to improve the quality of the triangulated mesh. We modify the shape and the connectivity between rock units in the basin, with the objective to reduce the computation time without significantly changing the physical response of the geological medium. These simplification techniques are applied in an investigation of site effects in the lower Var valley, a densely urbanized area located near the city of Nice (southeast of France). Numerical simulations of plane wave propagation in a heterogeneous 2-D profile are carried out with a discontinuous Galerkin finite element method. Five simplified meshes are generated and the impacts of the simplifications are analysed in comparison to the reference model. We compare the time solutions and the transfer functions obtained on the surface of the basin. The results show that the simplification procedures, in particular automatic modifications of the model, yield a significant performance gain, with a ratio higher than 55, while having a negligible impact on the ground motion response.

A scenario-based modeling of climate change impact on the hydrology of Ketar watershed, Central Rift Valley Basin, Ethiopia

A scenario-based modeling of climate change impact on the hydrology of Ketar watershed, Central Rift Valley Basin, Ethiopia

Assessing the Effect of Land/Use Land Cover and Climate Change on Water Yield and Groundwater Recharge in East African Rift Valley using Integrated Model

Study regionEast African Rift Valley basin. Study focusWater availability in the rift valley relies heavily on the discharge from the highlands to rivers that run to the rift floor. This research explores the effect of Land use/Land cover (LULC) and climate change on water yield and groundwater recharge (WYGR) using coupled SWAT-MODFLOW, which integrates Soil and Water Assessment Tool (SWAT) and Newton Modular Finite Difference Groundwater Flow (MODFLOW-NWT). The LULC change was analyzed using artificial neural network-based cellular automata. New hydrological insightsThe dominant LULC is cultivated land and expanded by 5% to the forest and grassland areas. The average temperature and precipitation are expected to rise by 8–11% and 3–6%, respectively. Climate change affects the spatiotemporal distribution of WYGR significantly, while LULC change has a trivial effect. Under the baseline scenario, the recharge was 10% of the average annual precipitation, but climate change is projected to reduce it by 47–53%. Water yield reduction up to 48% and change of perennial rivers to intermittent are expected in the coming decades. The region will experience water scarcity, emerging mainly from climate change.

A coupled study of ecological security and land use change based on GIS and entropy method-a typical region in Northwest China, Lanzhou.

Due to rapid population growth, industrialization, and urbanization, it is particularly important to address the increasingly serious ecological security issues in the process of urbanization, while it is important to grasp the impact of changes in land use structure on ecological security for scientific planning and to aid decision-making. As a typical valley basin industrialized city in northwest China, Lanzhou has complex geomorphology and climate with distinct regional characteristics, and the relationship between land use and ecological security is complex. In order to understand the current status and influencing factors of ecological security in various regions of Lanzhou, and to explore the intrinsic connection between ecological security and land use, this study constructed an ecological security evaluation index system based on the pressure-state-response (PSR) model with 14 secondary factors including natural, social, and economic factors. Based on the entropy method, GIS was used to analyze the trend of ecological security in each district and to clarify the coupling relationship between ecological security and land use change in Lanzhou City. The results show that the ecological security index (ESI) of Xigu District, a typical heavy industrial area, increased from 0.26 to 0.35, and the ESI of Yuzhong County, an agricultural development area, increased from 0.51 to 0.55 from 2000 to 2017. Low ESI was mainly distributed in areas with developed heavy industry, while high ESI was mainly found in areas with favorable natural conditions and mainly agricultural development. Economic factors were the leading factors affecting the ecological security of Lanzhou. In general, changes in land use structure and ecological security were inextricably linked, and the two influence and interact with each other. These results could provide some reference for the study of ecological security development and land use change in typical river valley cities and also provide a new path for other cities to study ecological security and the conservation of the ecological environment.

MORPHOMETRIC ANAYSIS OF THE MAJOR VALLEY SYSTEMS AROUND BENGALURU

The three major Valley systems of Bengaluru namely Vrishabhavathi Valley, Hebbal Valley and Kormangala-Challaghatta Valley houses many lakes and play a very important role in its hydrological processes. The morphometric analysis helps us to learn about the characteristics of the underlying rock type, pervious nature of soil, slope gradients, runoff behavior and water retention potential within the Valley systems. Morphometric analysis was carried out for Linear, areal and relief aspects. The Survey of India topographical maps and Digital Elevation Model data were used to prepare the base map and the drainage maps with the help of GIS software. The Strahler system of stream ranking was adopted. Among the three Valleys, Vrishabhavathi Valley is observed to be the largest Valley in terms of area and perimeter. Vrishabhavathi Valley basin has sixth order stream as the highest stream order where as the other two Valleys have fifth order stream as the highest order. The drainage pattern formed within the Valley systems was observed to be dendritic. The watershed shape factor showed that the Vrishabhavathi Valley is elongated in shape where as the K-C Valley and the Hebbal Valleys are less elongated in shape comparatively. The drainage density of the three Valleys revealed that they fall under coarse drainage density classification. The relief aspects of the three Valleys exhibit low reliefs indicating a flat surface. This helps in designing a sustainable management plan for the three major Valley systems in terms of their conservation and also ensure sustainable soil and water usage within the Valley systems.

Evaluation of the impacts of land use/cover changes on water balance of Bilate watershed, Rift valley basin, Ethiopia

Abstract Land use/cover change is one of the factors responsible for changing the water balance of the watershed by altering the magnitude of surface runoff, interflow, base flow, and evapotranspiration. This study was aimed at evaluating the impacts of land use/cover change on the water balance of Bilate watershed between 1989, 2002, and 2015. The water balance simulation model (WaSiM) was used to access the impacts of land use/cover change on water balance. The model was calibrated (1989–2003) and validated (2007–2015) using the streamflow of at Bilate Tena gauging station. The result of land-use dynamics showed land use/cover change has a significant impact on the water balance of the watershed: on runoff production, base flow, interflow, evapotranspiration, and total simulation flow. In the study watershed, the change in total simulated flow increased by 77.83%; surface runoff, interflow, and base flow increased by 80.23%, 75.69%, and 87.79% respectively; and evapotranspiration decreased by 6% throughout the study period (1989–2015). The results obtained from this study revealed that the watershed is under land/cover change that shows its impacts on hydrological processes and water balance. Thus, effective information regarding the environmental response of land use/cover change is important to hydrologists, land-use planners, watershed management, and decision-makers for sustainable water resource projects and ecosystem services. Therefore, the policy-makers, planners, and stakeholders should design strategies to ensure the sustainability of the watershed hydrology for the sake of protecting agricultural activities, and urban planning and management systems within the watershed area.

Morphometric Characteristics of the Aziana Valley Basin

The present study aims at examining quantitatively the morphometric characteristics of Iziana Valley basin that is located in the northern part of Iraq; particularly in south of Erbil Governorate. This basin is considered one of the small sub-basins where its valleys run on formations of the Triple and Quadrant Ages, which are represented by the Bay Hassan formations, and the sediments and mixed sediments of the cliffs, respectively. The area of ​​the Iziana basin amounts to (36.39 km2) whereas the percentage of its rotation reaches (0.17); a low percentage, which indicates that the basin diverges from the circular to the rectangular shape. The value of the elongation ratio of the basin reaches (0.38) while the terrain ratio of the basin is (0.03), a low percentage that entails the weakness of its erosion processes and the small volume of the carried and transported sediments. As for the relative topography of the basin, it was (1.08), which is also a low value. It indicates a relatively large area of ​​the basin and the impressive strides that it has made in its erosion cycle. The total river levels of the basin reach (5) ranks, and their numbers vary from one rank to another. Moreover, the total length of the drainage networks in the basin reached (187.4 km), and the prevailing drainage patterns in the basin are the tree and parallel patterns. The researcher has adopted spatial, formal, topographical, and river net-work properties for the purpose of first determining the shape of the basin, the stage of its erosion, its secondary basins, and its terrestrial features that have been developed as a result of the contrast between the erosion and sedimentation processes.

Coupling Fuzzy Multi-Criteria Decision-Making and Clustering Algorithm for MSW Landfill Site Selection (Case Study: Lanzhou, China)

The siting of Municipal Solid Waste (MSW) landfills is a complex decision process. Existing siting methods utilize expert scores to determine criteria weights, however, they ignore the uncertainty of data and criterion weights and the efficacy of results. In this study, a coupled fuzzy Multi-Criteria Decision-Making (MCDM) approach was employed to site landfills in Lanzhou, a semi-arid valley basin city in China, to enhance the spatial decision-making process. Primarily, 21 criteria were identified in five groups through the Delphi method at 30 m resolution, then criteria weights were obtained by DEMATEL and ANP, and the optimal fuzzy membership function was determined for each evaluation criterion. Combined with GIS spatial analysis and the clustering algorithm, candidate sites that satisfied the landfill conditions were identified, and the spatial distribution characteristics were analyzed. These sites were subsequently ranked utilizing the MOORA, WASPAS, COPRAS, and TOPSIS methods to verify the reliability of the results by conducting sensitivity analysis. This study is different from the previous research that applied the MCDM approach in that fuzzy MCDM for weighting criteria is more reliable compared to the other common methods.

Evaluation of the WEAP model in simulating subbasin hydrology in the Central Rift Valley basin, Ethiopia

BackgroundThe subbasin hydrologic behaviors have been altered by many natural and anthropologic factors such as climate change and land development activities. Model-based assessment can be used to simulate both natural hydrological processes, human-induced effects, and management strategies on water resources. For the Ketar subbasin, the WEAP (water evaluation and planning) hydrologic model was developed that aimed at (1) evaluating the application of the WEAP model in the Ketar subbasin, (2) evaluating the demonstration of the WEAP model using model efficiency evaluation criteria, and (3) simulating hydrological processes of the subbasin using the WEAP model.MethodsWEAP-based soil moisture method (rainfall-runoff) hydrology routine is comprised of a lumped, one-dimensional, two-layer soil water accounting that uses empirical functions to designate evapotranspiration, surface runoff, interflow, and deep percolation for a sub-unit at root zone. A catchment is considered as the smallest hydrologic response unit. The catchment’s surface hydrological balance is typically estimated by discretizing the catchment into multiple land uses for which water balance is estimated at root zone.ResultsThe monthly measured and simulated streamflow statistics showed a positive strong relationship with R2 of 0.82, NSE of 0.80, and IA of 0.95; and with R2 of 0.91, NSE of 0.91, and IA of 0.98 for calibration and validation periods respectively. Similarly, the mean monthly measured and simulated streamflow showed an agreement with R2 of 0.99, NSE of 0.97, and IA of 0.99, and R2 of 0.94, NSE of 0.93, and IA of 0.93 for the periods of calibration and validation respectively.ConclusionThe model has demonstrated the capability to represent the hydrologic dynamics of the subbasin both at monthly and mean monthly periods. In general, the overall model performance evaluation statistics show a very good agreement between measured and simulated streamflow at the outlet of the subbasin.

Geomorphological Assessment of the Viability of the Landforms in the Khalekan Valley Basin for Human Uses

The study aims to evaluating the landform in the khalakan basin and its to preparing appropriate model for the capacity of the lands by using remote sensing (RS) technology and geographic information system (GIS) by depending on function of (Wighted-Overlay) which can be considered as one of the significant function of GIS.
 And in order to achieve the aim of the study, eight layers have been extracted for preparing appropriate ground model. according to the importance of each layer which is used to determine the ability and they are: (geological formations, slope, splash erosion, soil, plant cover (NDVI), elevation and lineaments, geomorphological unit) layers which can be considered as the result of Intrusive and extrusive processes. After the processes of Overlaying, the study successfully produced a general map for the appropriateness ground which categorized the area into three levels of appropriateness: the level of high appropriateness with area of(9.34Km), the level of mid appropriateness with area of (70.34Km) and the level with no appropriateness with area of (4.957Km.

Morphometric Characteristics Of Al-Ratqa Valley Basin In The Western Anbar Plateau

Al-Ratqa Valley is located in the western part of Iraq within the western Anbar plateau, and it occupies an area of (5509) km2, and it consists of six secondary basins and they differ in all morphometric characteristics. The study also included the natural characteristics of the area that have an effect on the spatial and morphological characteristics and the characteristics of the drainage pattern. And the geomorphological processes and the types of soils in the region, as for the general slope of the basin, it is from the west and southwest towards the east and northeast, as for the general climate of the region, it is desert, hot dry in summer and cold rainy in winter, and the number of basin ranks reached seven ranks, and that the quantitative method was followed in the geomorphological and morphometric analysis By relying on digital data obtained from topographic maps, aerial photos and satellite lmages, in the analysis of the morphometric characteristics of the basin drainage pattern and the spatial, morphological and topographic characteristics of Al-ratqa Valley basin

Geomorphometric Analysis of Abu Dalaih Valley Basin Using Geomatics Techniques and the Possibility of Investing it for Water Harvesting Purposes

The study included a hydrogiomorphological evaluation of Abu Dalaya basin in Al-Jezira region for the water harvesting purposes, which an area reached (227 km2). Abu Dalaya basin contains three secondary basins, which are almost similar in their morphometric and hydrological characteristics, and most of them are close to the rectangular shape. The researcher used the integration between several data, such as Remote Sensing (RS) data, climate and ground data for the study area and its region, whereby the outputs from maps and figures were obtained by using Geographic Information System (GIS). For the purposes of water harvesting, the study adopted (SCS-CN) model to estimate the volume of surface runoff, and the results indicated that the study area is characterized by high runoff due to the presence the soils type(C) that are characterized by their inability to infiltrate water into the soil.The hourly data for the season (2018-2019) showed that the amounts of rain were large, ranging between (652-761 mm). Thus, this amount of water must be preserved, and thus four sites were chosen for the construction of earth dams in the study area. In addition, the results of those proposed dams for water harvesting proved that the quantities of water storage in them are uneven, but very large and sufficient for the various types of future investments