High Drainage Density Research Articles

Influence of Lithology and Biota on Stream Erosivity and Drainage Density in a Semi‐Arid Landscape, Central Chile

AbstractDrainage density is a fundamental landscape feature that determines the length scale for hillslope sediment transport and results from the competition of diffusive hillslope and advective stream incision processes, whose efficiencies are known to vary with rock type but are notoriously difficult to quantify. Here, we present a comprehensive analysis of a catchment in semi‐arid Central Chile, where landscapes with different drainage densities, but equal tectonic and climatic conditions, have formed on three neighboring granitoid plutons (a monzogranite and two diorites). We combined topographic analysis of a 1‐m digital elevation model with 10Be‐derived denudation rates to estimate stream erosivity and soil diffusivity in the different landscapes. We find that the higher drainage density in the monzogranite is primarily due to higher stream erosivity, whereas soil diffusivity is similar between rock types. Remote sensing data from Landsat imagery confirm field observations of higher vegetation cover in the diorites, especially with regard to deeper‐rooted shrubs, which may result in increased infiltration. Based on geochemical and compositional analyses, we link vegetation differences to a relatively higher abundance of plant‐essential elements in the diorite bedrock. Additionally, the monzogranite's composition and crystal grain size supports more intense physical weathering and leads to a smaller observed hillslope grain size, which increases its erodibility. We conclude that subtle differences in composition and grain size can have a significant impact on stream erosivity and drainage density. Our results demonstrate the importance of taking lithology into account when interpreting fluvial networks and topographic metrics in slowly eroding landscapes.

Morphological Analysis of River Characteristics in Musi Rawas Utara Regency

Effective watershed management requires the efficient collection, storage, and use of runoff water, as well as the recharge of groundwater. This study will employ morphometric analysis to determine the characteristics of the rivers flowing through one of the districts of the Province of South Sumatera, Musi Rawas Utara (Muratara). Using DEM data and GIS software, this study conducted a quantitative-descriptive analysis to obtain quantitative information about the watershed. The acquired numbers are interpreted descriptively to provide a description of the watershed's characteristics and their implications for rivers in Muratara.The eighth-order rivers of Muratara Regency are classified as major rivers. A mean bifurcation ratio (Rb) of 3.98 indicates that geological features have no effect on the typical flat drainage pattern. On average, the drainage density of the watersheds was moderate, but a few locations had a very high drainage density range, indicating their erodibility. The basins of rivers with low circularity and elongation ratios (0.19 and 0.48, respectively) are elongated and have a steep slope. The morphometric research reveals that the Muratara rivers have abundant water resources and are also predicted to experience numerous water-related disasters. Using morphometric knowledge, however, the local government could develop mitigation and planning systems for river management. Future measures must include ensuring that adequate drainage systems are in place and that all construction adheres to the principles of proper land management.

GIS based Soil Erosion Susceptibility Mapping in Middle Himalayas using MCDM: A Case Study of Rajouri District.

The Pirpanjal range, nestled within the Himalayan region, confronts substantial soil erosion challenges owing to its diverse topography and the inherent instability of geological formations. This study focuses on the Rajouri region, to assess soil erosion susceptibility and spatially prioritize vulnerable zones. Utilizing a Geographical Information System (GIS)-based approach, we employed the Analytic Hierarchy Process (AHP) and the Weighted Sum Method (WSM). Various datasets, including precipitation records, geological maps, soil maps, and satellite imagery, were incorporated to derive eleven critical factors. These factors encompassed topographical derivatives; land use and land cover (LULC), soil properties, drainage patterns, rainfall data, lithological characteristics, wetness index, and the vegetative health of the area. The methodology employed yielded unbiased and reliable ratings and weightages, as substantiated by a Consistency Ratio (CR) of 0.095. The results reveal that 41% of the total area in the study region is exceedingly vulnerable to soil erosion. Slope variations range from 0 to 67.14 degrees, delineating high and very high susceptibility zones spanning 531.79 km² (19.82%) and 316.20 km² (11.78%) of the area, respectively. Additionally, assessments based on the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI) underscore the severity of soil erosion, covering 40% and 25% of the highly susceptible zones, respectively. High drainage density and curvature zones were identified in 13% and 31% of the study area, respectively. This comprehensive study contributes valuable insights for the planning and implementation of effective soil conservation measures in the Rajouri region.

Prevalence and Incidence of Hepatitis E Infection in China

Background and aimsChina is an endemic area for HEV infection. Estimating the prevalence and incidence of HEV infection in China plays a pivotal role in informing public health policies to prevent and control hepatitis E. This study aimed to investigate the prevalence of anti-HEV IgG and incidence of HEV seroconversion in China. MethodsThis study was based on the Meinian health check-up database in China. Participants who underwent testing for anti-HEV IgG at check-up centers in 24 provinces between 2017 and 2022 were included. In the cross-sectional analyses, overall prevalence and stratified prevalence in subpopulations with various characteristics were estimated and standardized according to the 2020 census of the Chinese population. In the longitudinal analyses, the occurrence of anti-HEV IgG positivity during the follow-up was defined as an incident HEV seroconversion. Overall and stratified incidence rates were estimated and expressed as per 100 person-years. Poisson regression was used to explore risk factors associated with HEV seroconversion. Results85,238 and 11,154 participants were included in the cross-sectional and longitudinal analyses, respectively. The prevalence of anti-HEV IgG in the general population was 18.02%. During a median follow-up of 1.2 years, the incidence rate of HEV seroconversion was 1.79 per 100 person-years. Age ≥ 60 years, low socioeconomic status, living in coastal areas, living in areas with high drainage density, and living in areas with high anti-HEV IgG prevalence were independent risk factors for HEV seroconversion. ConclusionsOur findings would help inform policy making for hepatitis E prevention and control in China, as well as in other endemic regions of the world.

Flood Susceptibility Mapping for Kedah State, Malaysia: Geographics Information System-Based Machine Learning Approach

ABSTRACT Background: The world economy is significantly impacted by floods. Identifying flood risk is essential to flood mitigation techniques. Aim: The primary goal of this study is to create a geographic information system (GIS)-based flood susceptibility map for the study area. Methods: Ten flood-influencing factors from a geospatial database were taken into account when mapping the flood-prone areas. Every element demonstrated a robust relationship with the probability of flooding. Results: The highest contributing elements for the flood disaster in the study region were drainage density, distance, and the curvature. Flood susceptibility models’ performance was validated using standard statistical measures and AUC. The ROC curves demonstrated that all ensemble models had good performance on the validation data sets (AUC = >0.97) with high accuracy scores of 0.80. Based on the flood susceptibility maps, most of the northwest regions of the study area are more likely to flood because of low land areas, areas with a lower gradient slope, linear and concave shape curvature, high drainage density with high rainfall, more “water bodies,” “crops land,” and “built areas,” abundance on sea and surface water, and Quaternary types of soil feature and so on. The very high flood susceptibility class accounts for 18.2% of the study area, according to the RF-embedding model, whereas the high, moderate, low, and very low susceptibility classes were found at about 20.0%, 24.6%, 24.3%, and 12.9%, respectively. Conclusion: In comparison with other commonly used applied approaches, this research presents a novel modeling approach for flood susceptibility that integrates machine learning and geospatial data. It has been found to be stronger and more efficient, highly accurate, has good prediction performance, and is less biased. Overall, our research into machine learning-based solutions points in a positive path technologically and can serve as a reference manual for future research and applications for academic specialists and decision-makers.

Morphometric Analysis Using Remote Sensing and Geographical Information System: A Case Study of Nawagarh Watershed of Chhattisgarh, India

The study highlights the suitability of a GIS-based approach for evaluating morphometric parameters. It focuses on the quantitative analysis of morphometric characteristics within thirteen sub-watersheds of the Nawagarh watershed, which originates from the Seonath river catchment in the Mahanadi basin in Chhattisgarh, India. The Nawagarh watershed spans an area of 2647.27 km2. Its outlet is located at 21°46'10" N Latitude and 81° 48’43” E Longitude. The Nawagarh watershed covers four districts in Chhattisgarh - Kabirdham, Bemetara, Baloda Bazar, and Mungeli. The analysis reveals the relative qualities of the sub-watersheds in terms of hydrological response. The Nawagarh watershed features a dendritic drainage network with 2760 streams of different orders. The slope of the land directly affects water absorption and drainage. High relief ratio 0.032 in SWD1 and SWD3 indicates rapid concentration, rapid stream flow, and greater susceptibility to erosion than other sub watersheds. The drainage density is 0.80 km-1, which is close to 1 km-1, indicating that the basin has a nearly high drainage density, which demonstrate that the location with impermeable weak subsurface material and has high relief. The elongated shape with the values of form factor (0.39), circulatory ratio (0.28) and elongation ratio (0.69), indicated that the Nawagarh watershed is more elongated with lower peak flow of long duration having low permeability. The drainage density in the basin is relatively high, suggesting a significant drainage network. The study emphasizes the need for effective erosion control methods in the Nawagarh watershed to protect the land.

Morphometric analysis of the Middle Tuirial watershed, Mizoram, India and its significance for soil loss risk

This study aims to highlight the quantitative analysis of Middle Tuirial watershed in Mizoram, India and its significance for soil loss risk. In addition to understanding landscape evolution and hydrological characteristics of the river basin, it is crucial to implement appropriate soil and water conservation practices, to reduce further soil erosion risk in the basin. Linear, areal and relief aspects of morphometric parameters were analyzed using a survey of India topographical maps, advanced land observing satellite (ALOS) phased array type L-band synthetic aperture radar (PALSAR) digital elevation model (DEM), and geographic information system (GIS). The study reveals a high drainage density of 5.22 km/km2 and stream frequency of 10.58 km2, which denotes the basin exhibits high surface run-off with low groundwater recharge. In addition, it has 0.6 form factor, 0.3 elongated ratio and 0.43 circularity ratio indicating a highly elongated shape of the basin. Furthermore, the hypsometric integral values of 0.48 with an s-curve show the basin has attained a mature stage of landscape evolution.

Geomorphologic risk zoning to anticipate tailings dams' hazards: A study in the Brumadinho's mining area, Minas Gerais, Brazil

The use of tailings dams in the mining industry is recurrent and a matter of concern given the risk of collapse. The planning of tailings dam's emplacement usually attends construction design criteria and site geotechnical properties, but often neglects the risk of installing the depositional facilities in potentially unstable landscapes, namely those characterized by steep slopes and(or) high drainage densities. In order to help bridging this gap, the present study developed a framework model whereby geomorphologic vulnerability is assessed by a set of morphometric parameters (e.g., drainage density; relief ratio; roughness coefficient). Using the Ribeirão Ferro-Carvão micro-basin (3265.16 ha) as test site, where six dams currently receive tailings from the mining of iron-ore deposits in the Brumadinho region (Minas Gerais, Brazil) and one has collapsed in 25 January 2019 (the B1 dam of Córrego do Feijão mine of Vale, S.A.), the risk of dam instability derived from geomorphologic vulnerability was assessed and alternative suitable locations were highlighted when applicable. The results made evident the location of five dams (including the collapsed B1) in high-risk regions and two in low-risk regions, which is preoccupying. The alternative locations represent 58 % of Ribeirão Ferro-Carvão micro-basin, which is a reasonable and workable share. Overall, the study exposed the fragility related with tailings dams' geography, which is not restricted to the studied micro-basin, because dozens of active tailings dams exist in the parent basin (the Paraopeba River basin) that can also be vulnerable to geomorphologically-dependent hydrologic hazards such as intensive erosion, valley incision or flash floods. Attention to this issue is therefore urgent to prevent future tragedies related with tailings dams' breaks, in the Paraopeba River basin or elsewhere, using the proposed framework model as guide.

Flood hazard mapping using GIS-based statistical model in vulnerable riparian regions of sub-tropical environment

Floods are a recurrent natural calamity that presents substantial hazards to human lives and infrastructure. The study indicates that a significant proportion of the study area, specifically 27.05%, is classified as a moderate flood risk zone (FRZ), while 20.78% is designated as high or very high FRZ. The region’s low and very low FRZ are classified at 52.17%. The GIS-based AHP model demonstrated exceptional predictive precision, achieving a score of 0.749 (74.90%) as determined by the AUC-ROC, a widely used statistical evaluation tool. The current study has identified areas with high FRZ in the affected CD blocks, which are situated in low-lying flood plains, regions with gentle slopes, high drainage density, high TWI, low NDVI, high MNDWI, areas with high population density, intensive agricultural land. The findings of this research offer significant perspectives for decision-makers, city planners, and emergency management agencies in devising efficient measures to mitigate flood risks.

Flood Vulnerability Assessment Across Alaknanda River Basin using GIS-based Combined Analysis of Geomorphometric Approach and MCDM-AHP

Abstract Floods are one of the most devastating natural disasters, causing land destruction, economic loss, and massive disruptions to humans. The present study was conducted in the Alaknanda river basin with medium to high drainage density and stream frequency. The flood vulnerable zones (FVZ) are identified using geomorphometric analysis, and flood vulnerability zones are identified through analytical hierarchy processes (AHPs). Three factors, such as linear, relief, and aerial, have been used in the geomorphometric analysis of the Alaknanda basin. The weights were assigned on a scale of 1 for flood-induced factors such as slope (0.386), rainfall (0.192), drainage density (0.129), LULC (0.096), geology (0.077), soil (0.064), and DEM (0.055) have been determined using 7×7 decision matrix of multi-criteria decision making- analytical hierarchy processes (MCDM-AHP) model accounting for their varying importance from high to low priorities. A consistency ratio (CR) of 0.083 (less than 0.1) signifies the acceptance of the weights derived in the case. The high shape index, form factor, and rotundity factor indicate the basin allows quick drainage of surface runoff with a lesser time of concentration; as a result, sharp peaks of the hydrograph will be obtained at the outlet of the basin. However, most of the basin area is under the moderate vulnerability category, while the entire river banks along the valley are the most vulnerable. Additionally, a small-scale sociological study indicates that for a population that resides close to highly susceptible locations, temporary relocation is the most common strategy.

Evaluating geo-hydrological environs through morphometric aspects using geospatial techniques: A case study of Kashang Khad watershed in the Middle Himalayas, India

The present study analyzes the geo-hydrological behaviour of the Kashang khad basin of the satluj river system in Kinnaur district, Himachal Pradesh. The major source of water in the region is the snowmelt, which contributes to the evolution of a drainage pattern. It highlights the importance of ASTER GDEM and satellite images for assessing and understanding the various geo-hydrological parameters such as drainage analysis, and topographic analysis for better basin management. Hydrological modelling of ArcGIS 10.5 has been used for the delineation and analysis of basins using SRTM DEM with 30 m resolution. Morphometric parameters like linear, relief, and aerial further help in the micro-level study of its physiographic characteristics and structural control of flow along with runoff, which can help predict floods, their extent, and intensity. It was found that the basin had a dendritic pattern with uniform lithology. The stream order ranges from 1st order to 5th order signalling homogeneity in texture and medium to high drainage density meaning permeable soil and good surface runoff. The drainage texture of 2.19 indicates the basin is prone to weathering and erosion. The bifurcation ratio ranges from 4.43 to 5.23, with a mean Rb of 4.82 showing the structural control on the elongated basin with Re of 0.56. The ASTER DEM and sophisticated morphometric attributes and hydrological environs can be effectively utilized in watershed management and other hydrological studies in higher mountainous regions.

Multi-Sensor Remote Sensing Data and GIS Modeling for Mapping Groundwater Possibilities: A Case Study at the Western Side of Assiut Governorate, Egypt

Groundwater is an essential natural resource and it has a significant role in the development of dry lands. It is the main source of fresh water in arid and semi-arid regions. The present study investigates groundwater potentiality in the western part of Assiut Governorate, Egypt using advanced remote sensing and geospatial techniques along with hydrological data and field validation. The adopted method provides a low-cost and highly effective tool that can be combined with the conventional land-based approach for mapping Groundwater Potentiality. The study aims to determine the groundwater probability and recharging zones based on the contribution of some physiographic variables that influence groundwater storage. Therefore, multi-sensors remote sensing data from ASTER, Landsat-8, MODIS, Shuttle Radar Topography Mission (SRTM), Tropical Rainfall Measuring Mission (TRMM), and Radarsat-1 were accustomed to extract several geospatial thematic layers (variables). These layers include elevation, slope, curvature, drainage density, topographic wetness index, surface roughness, frequency of thermal anomaly, accumulated precipitation, Land Use/Land Cover (LULC), and lineament density. The produced layers are then scaled and weighted based on their contributions to the recharge of near-surface (unconfined) groundwater aquifers through infiltration and percolation processes. The Simple Additive Weight (SAW) method was utilized to aggregate all the weighted layers for creating the Groundwater Potentiality map. This aggregated grouped map was then classified into 5 classes, from very high to very low groundwater potentiality zones. The results show that the high Groundwater Potentiality was associated with low terrain, high surface ruggedness, high drainage and lineament densities, and relatively close to thermal anomalies in wadi deposits, and adjacent sandy areas. The remote sensing results were validated using comprehensive field observations including, pumping tests, water wells data, and vegetation patterns in the study area. The study concluded that a groundwater possibility map based on geospatial techniques and remote sensing data can provide a robust tool in groundwater exploration, and consequently, it can be adopted elsewhere in arid regions.

Badland erosion susceptibility mapping using machine learning data mining techniques, Firozkuh watershed, Iran

Badlands are landforms related to runoff, with dissected V-shaped valleys, short steep slopes, and high drainage density, and results from a very important type of erosion that develops due to a complex interaction of conditioning factors, including climatic, hydrologic, geologic and soil properties, topographic characteristics, and land use. The main goals of this study were (1) create badland susceptibility maps of the Firozkuh watershed and five machine learning algorithms (models)—functional discriminant analysis (FDA), generalized linear model (GLM), mixture discriminant analysis (MDA), multivariate adaptive regression spline (MARS), and support vector machine (SVM); and (2) compare the accuracy of these models. Sixteen conditioning factors were chosen to model and classify badland susceptibility based on a literature review, data availability, and field surveys. Model accuracy was assessed using ROC curve and AUC analyses. The analyses showed that SVM was “excellent,” MARS was “very good,” MDA was “good,” and GLM and FDA were “moderate” in classification accuracy. The land area of the very high and high classes ranged from 31 to 51% of the Firozkuh watershed for the GLM and SVM models, respectively. This indicates that badland erosion is a very important problem in the study area. Climatic, hydrologic, geologic, topographic, and soil conditions as well as land use changes render the Firozkuh watershed prone to badland formation and soil erosion which results in substantial socioeconomic losses. Badland susceptibility mapping is an important tool that can be used to improve managing future badland erosion in the Firozkuh watershed and other areas affected by badland erosion.

Analytic Hierarchy Process (AHP) Based Soil Erosion Susceptibility Mapping in Northwestern Himalayas: A Case Study of Central Kashmir Province

The Kashmir Valley is immensely susceptible to soil erosion due to its diverse topography and unstable geological formations in the Himalayan region. The present study helps in assessing the spatial distribution and prioritizing soil erosion zones in the Central Kashmir region covering the Sindh and Dachigam catchments. The study implemented the GIS-based analytic hierarchy process (AHP) and weighted sum method (WSM) using datasets of precipitation, geological map, soil map, and satellite imagery and derived eleven factors (topographical derivatives, LULC, soil, drainage, rainfall, lithology, wetness index and greenness of an area). The ratings and weightage were proven to be unbiased and reliable based on the observed value of the consistency ratio (CR) (i.e., 0.07). The study depicts 41% of the total area to be extremely vulnerable to soil erosion. The slope varies from 0–62° with mean of 22.12°, indicating 467.99 km2 (26%) and 281.12 km2 (15%) of the area under high and very high susceptible zones, respectively. The NDVI and NDWI maps indicate soil erosion severity covering an area of 40% and 38%, respectively, in highly susceptible zones. High drainage density and curvature zones were observed in 18.33% and 22.64% of the study area, respectively. The study will assist in the planning and implementation of conservation measures.

Assessing integrated agricultural livelihood vulnerability to climate change in the coastal region of West Bengal: Implication for spatial adaptation planning

In Southeast Asia, the West Bengal coastal region is one of the significant hotspots of climate-induced vulnerability. This article defines vulnerability as a function of exposure, sensitivity, and adaptive capacity. We selected 43 subcomponent indicators under nine major components for constructing the Integrated Agricultural Livelihood Vulnerability Index (IALVI). Understanding the spatial distribution of IALVI to climate change is vital to formulate proper sustainable adaptation strategies for the future. Results revealed that high to very high vulnerability in the south and southeastern coastal C.D. Blocks due to high exposure and high sensitivity and agricultural livelihood of 5.02 million people were highly vulnerable to the adverse effect of climate change. On the contrary, moderate to low vulnerability is experienced in the western and northern parts of the region due to less exposure, less sensitivity, and high adaptive capacity. This study applies geospatial techniques and examines the spatial distribution of climate change vulnerability in the coastal region of West Bengal. The most vulnerable region in this study area comprises a gentle slope, low elevation, high drainage density, and poor socio-economic conditions. Consequently, several adaptation methods, such as a better cyclone shelter, embankments, a more robust transportation and communication system, and improved healthcare facilities, may help to raise the level of adaptive capacity in the vulnerable regions. These findings will be helpful for policymakers in formulating proper climate risk mitigation strategies in coastal West Bengal. To validate the secondary results primary investigation was also done in this study.

Climatic influence on the expression of strike-slip faulting

Abstract Earthquakes on strike-slip faults are preserved in the geomorphic record by offset land-forms that span a range of displacements, from small offsets created in the most recent earthquake (MRE) to large offsets that record cumulative slip from multiple prior events. An exponential decay in the number of large cumulative offsets has been observed on many faults, and a leading hypothesis is that climate controls the rate of decay. We present offset measurements compiled from 31 studies of strike-slip faults with evidence of multiple paleoearthquakes and corresponding climatic and tectonic information to test this hypothesis. Both the global compilation and numerical landscape evolution modeling reveal that the decay rate in large offsets is negatively correlated with mean annual precipitation. Faults in dry regions with high drainage density more commonly preserve small MRE offsets, and faults in wet regions with lower drainage density more commonly preserve a mix of small MRE and large cumulative offsets. Geomorphology of faults in different climates supports this result and illustrates precipitation's effect on the development and preservation of off-set channels. Our findings imply that current and past climate affect how displacement on strike-slip faults is recorded and interpreted to inform earthquake history.

Topography and rainfall coupled landscape evolution of the passive margin of Sahyadri (Western Ghats), India

The passive margin of the Indian peninsula, revered as Sahyadri (Western Ghats) from time immortal, stretches along the western margin of the Indian Craton. It acts as an orographic barrier, and the frontal part of this continental-scale escarpment receives most of the rainfall, whereas the plateau top remains dry; this makes a case to study the processes of landform evolution in a climatically active and tectonically quiescent region. In our study, we demonstrated the modification of the Sahyadri with the annual forcing of the Indian Summer Monsoon (ISM). Seven major perennial river basins having higher drainage density and flowing on a lithologically varied terrain were studied using the SRTM 30 m data. The morphometric studies carried out in these basins, and the topographical analyses of the region offer the development of drainage systems on varied lithological terrain with diverse geological history. We demonstrated how the drainage basin erosion is moderated by the headward erosion by the streams as forced by the runoff water, probably by local base-level fluctuations and the forcing of ISM. The modification of the basin margin, i.e., drainage divide migration, is primarily affected by precipitation, whereas the lithological and structural factors have a second-order control on the overall retreat of the water divide.

Morphometric, Meteorological, and Hydrologic Characteristics Integration for Rainwater Harvesting Potential Assessment in Southeast Beni Suef (Egypt)

In arid areas, the forecast of runoff is problematic for ungauged basins. The peak discharge of flashfloods and rainwater harvesting (RWH) was assessed by the integration of GIS, the RS tool and hydrologic modeling. This approach is still under further improvement to fully understand flashflood and rainwater harvesting potentialities. Different morphometric parameters are extracted and evaluated; they show the most hazardous sub-basins. Vulnerability potential to flooding is high relative to steep slopes, high drainage density, and low stream sinuosity. Using hydrologic modeling, lag time, concentration time, peak discharge rates, runoff volume, rainfall, and total losses are calculated for different return periods. The hydrologic model shows high rainfall rates, and steep slopes are present in the southeastern part of the study area. Low rainfall rates, moderate–high runoff, and gentle slopes are found in the central and downstream parts, which are suitable sites for rainwater harvesting. An analytic hierarchy process is utilized for mapping the best sites to RWH. These criteria use land-cover, average annual max 24 h rainfall, slope, stream order, and lineaments density. About 4% of the basin area has very high potentialities for RWH, while 59% of the basin area has high suitability for RWH. Ten low dam sites are proposed to impact flooding vulnerability and increase rainwater-harvesting potentialities.

Morphometric Analysis of the Rawandoz River Basin, Erbil, Kurdistan Region, Iraq

In this research detailed morphometric investigation of the Rawanduz river basin in the northeastern part of Erbil, Iraq has been made. The study area covers an approximately 977.68 km2. Digital Elevation Model data (DEM 12.5 m), Remote sensing and GIS methods were used for studying basin morphometric parameter such as linear, aerial, and relief aspects, as well as to delineate lineaments in the study area.The results reveal that there is an opposite correlation between stream order, stream number, and length of streams in the research region basin by R2 values (R2 = 0.77 and 0.73) which is good value depending on statistical analysis. Streams were also ordered, with a total of 6376 streams totaling 2376.4 km in length. The basin's elongation ratio (0.54), circulation ratio (0.45), and form factor (0.23) data suggested that it was semi-elongated to elongated in nature, with poor permeability material, high relief, steep slopes, and main drainage pattern types affected by lineaments and fracture traces. In the research region, the stream frequency value is 5.6 km2 which is a high value suggesting impermeable lithology and enhanced surface runoff in the basin area. The drainage density in the investigated area is 2.43 km-1. The Rawanduz river basin's high drainage density value (2.43 km-1) reveals a fine drainage texture value (38.77 km-3). This study will help decision-makers and local residents to benefit from the resources for the sustainable development of the basin area.

Potential flood-prone area identification and mapping using GIS-based multi-criteria decision-making and analytical hierarchy process in Dega Damot district, northwestern Ethiopia

Flood is one of the natural hazards that causes widespread destruction such as huge infrastructural damages, considerable economic losses, and social disturbances across the world in general and in Ethiopia, in particular. Dega Damot is one of the most vulnerable districts in Ethiopia to flood hazards, and no previous studies were undertaken to map flood-prone areas in the district despite flood-prone areas identification and mapping being crucial tasks for the residents and decision-makers to reduce and manage the risk of flood. Hence, this study aimed to identify and map flood-prone areas in Dega Damot district, northwestern Ethiopia, using the integration of Geographic Information System and multi-criteria decision-making method with analytical hierarchy process. Flood-controlling factors such as elevation, slope, flow accumulation, distance from rivers, annual rainfall, drainage density, topographic wetness index, land use and land cover, Normalized Difference Vegetation Index, soil type, and curvature were weighted and overlayed together to achieve the objective of the study. The result shows that about 86.83% of the study area has moderate to very high susceptibility to flooding, and 13.17% of the study area has low susceptibility to flooding. The northeastern and southwestern parts of the study area dominated by low elevation and slope, high drainage density, flow accumulation, topographic wetness index, and cropland land use were found to be more susceptible areas to flood hazards. The final flood susceptibility map generated by the model was found to be consistent with the historical flood events on the ground in the study area, revealing the method’s effectiveness used in the study to identify and map areas susceptible to flood.