C.A. Odiji; O.M. Aderoju; M.C. Ekwe; D.T. Oje; J.O. Imhanfidon
Abstract
Runoff assessment and estimation is crucial for watershed management as it provides information that is needed to expedite the course of watershed planning and development. The most commonly used model due to its simplicity and versatility in runoff estimation is the soil conservation service curve number ...
Read More
Runoff assessment and estimation is crucial for watershed management as it provides information that is needed to expedite the course of watershed planning and development. The most commonly used model due to its simplicity and versatility in runoff estimation is the soil conservation service curve number developed by the United States Department of Agriculture. The study estimates the surface runoff of Upper Benue watershed using a geospatial based soil conservation service curve number model. Datasets utilized for this purpose are; Rainfall, land use, digitial elevation model and FAO-Soil. The soil and land use data were intersected to create the curve number grid and database. The curve number grid combined with the mean annual rainfall data from 1990 – 2017 was used to estimate runoff. The result revealed that 61.5% of rainfall was direct runoff while 38.5% of the rainfall was retained by tree/plant cover and soil. The average curve number for the normal condition was calculated to be 80.1 while the dry and wet season was 59.6, and 93.2 respectively. The average runoff volume for 27 years was estimated to be 69,887.43mm3. A correlation coefficient of 0.79 was found for the relationship between rainfall and runoff. The research highlights the importance of geospatial technique when integrated with soil conservation service curve number to estimate runoff conditions in Upper Benue Watershed.
B.S. Igulu; E.E. Mshiu
Abstract
The lack of hydrological data for urbanizing watersheds in developing countries is one of the challenges facing decision making. Msimbazi River is located in the city center of Dar es Salaam and is highly influenced by human activities; this includes dense populations that are characterized by informal ...
Read More
The lack of hydrological data for urbanizing watersheds in developing countries is one of the challenges facing decision making. Msimbazi River is located in the city center of Dar es Salaam and is highly influenced by human activities; this includes dense populations that are characterized by informal settlements. The catchment is currently undergoing flooding, which triggers a dilemma in its surface runoff trending. This study aimed to simulate rainfall-runoff of an urbanizing Msimbazi watershed that will provide an understanding of hydrological data including peak flows and discharge volumes of Msimbazi River. The data used in the study include soil, rainfall, DEM and land use. HEC-GeoHMS and ArchHydro tools in ArcGIS were used to generate hydrological inputs to be used in the HEC-HMS interface. The resulted sub-watersheds have high CN values ranging from 70 to 90 implying the possibility of high runoff potential. Sub-watershed W620 indicates the highest runoff, among others with the highest runoff of 290mm for the year 2015. The peak flow on the river indicates the value ranging from 7.2 m3/s to 30m3/s with the highest values being on the downstream. The overall trend indicates an increasing surface runoff and peak flow in sub-watersheds from 1985 to 2015. Simulated results in this study were validated with the observational data of the catchment recorded in 2017. Given that most of the rivers in Tanzania are ungauged, the approach applied in this study can be used to enhance decision making on settlement planning, water resource, and disaster management in the currently observed urbanizing areas.
H.T. Abdel Hamid; W. Wenlong; L. Qiaomin
Abstract
Flash flood has been increasing in the Khartoum area, Sudan due to geographical conditions and climatic change as heavy rainfall and high temperature, therefore the present work tried to estimate the sensitivity of flash flood. The present work proposes an advanced technique of flood sensitivity mapping ...
Read More
Flash flood has been increasing in the Khartoum area, Sudan due to geographical conditions and climatic change as heavy rainfall and high temperature, therefore the present work tried to estimate the sensitivity of flash flood. The present work proposes an advanced technique of flood sensitivity mapping using the method of analytical hierarchy process. Ten factors as elevation, slope, distance from the network, land use, density of the drainage, flow accumulation, surface roughness, stream power index, topographic wetness index and curvature of the topography were digitized and then contributed in the mapping of Flash flood. Remote sensing data were integrated with analytical hierarchy process to determine the flood sensitive area in Sudan. The model was applied and completed as the consistency ratio was mostly reasonable (< 0.1). Based on the proposed model, about 75.56 Km2 (12.26 %), 156.14 Km2 (25.33%), 169.89 Km2 (27.56 %), 141.40 Km2 (22.94 %) and 73.50 Km2 (11.92 %); were classified as no susceptible, low susceptible, high susceptible, moderate susceptible and very highly susceptible to flooding. The present study showed a high variation in flood sensitivity due to climatic change and geographic condition. This index can be modified and applied in areas of the same characteristics of climatic conditions as one of the main recommendation in the study area. The study showed that poor infrastructure and lack of preparedness were the main causes of the disaster of flood in Sudan. This study merely demonstrated the critical analysis of geospatial mapping in proper mitigating, sustainable development and great monitoring the negative effects of flooding along the Khartoum region to reduce hazards of flood.
V. Anand; B. Oinam
Abstract
Hydrological components in a river basin can get adversely affected by climate change in coming future. Manipur River basin lies in the extreme northeast region of India nestled in the lesser Himalayan ranges and it is under severe pressure from anthropogenic and natural factors. Basin is un-gauged as ...
Read More
Hydrological components in a river basin can get adversely affected by climate change in coming future. Manipur River basin lies in the extreme northeast region of India nestled in the lesser Himalayan ranges and it is under severe pressure from anthropogenic and natural factors. Basin is un-gauged as it lies in remote location and suffering from large data scarcity. This paper explores the impact of climate change towards understanding the inter-relationships between various complex hydrological factors in the river basin. An integrated approach is applied by coupling Soil and Water Assessment Hydrological Model and Hadley Center Coupled Model based on temperature, rainfall and geospatial data. Future representative concentration pathways 2.6, 4.5 and 8.5 scenarios for 2050s and 2090s decades were used to evaluate the effects of climatic changes on hydrological parameters. Both annual mean temperature and annual precipitation is predicted to be increased by 2.07oC and 62% under RCP 8.5 by the end of 21st century. This study highlights that change in meteorological parameters will lead to significant change in the hydrological regime of the basin. Runoff, actual evapotranspiration and water yield are expected to be increased by 40.96 m3/s, 52.2% and 86.8% respectively under RCP 8.5. This study shows that water yield and evapotranspiration will be most affected by increase in precipitation and temperature in the upper and middle sub-basins. Different region within the basin is likely to be affected by frequent landslides and flood in coming decades.
G.R. Puno; R.C.C. Puno
Abstract
Geomorphometric features and land use/land cover are essential in the context of watershed prioritization for resources conservation and protection. Watersheds in tropical regions like the Philippines are under threat of degradation due to the combined effects of uncontrolled agricultural activities ...
Read More
Geomorphometric features and land use/land cover are essential in the context of watershed prioritization for resources conservation and protection. Watersheds in tropical regions like the Philippines are under threat of degradation due to the combined effects of uncontrolled agricultural activities in the uplands and frequently increasing erosive precipitations brought about by climate change. Watershed managers are challenged with these pressing issues and concerns because most watersheds have no sufficient data as a basis for decision making. This paper presents the method of analyzing the different geomorphometric features and the existing land use or land cover to assess the propensity of the watershed against erosion so that areas needing immediate treatment can be prioritized. Arbitrarily, fourteen subwatersheds coded as SW1 to SW14 were delineated using a digital elevation model and geographic information system tool. Geomorphometric features categorized as areal aspect, relief features, and channel morphology parameters were generated and analyzed. Parameters having direct and inverse effect to erosion risk was used as the criteria in the ranking process. Land use/land cover was added to geomorphometric parameters to come up with compound values for final prioritization. Results showed that SW13, SW14, and SW4 were classified under very high priority implying focus for appropriate management actions while SW10, SW6, and SW7 were classified under very low priority suggesting favorable environmental condition in these areas. The study provides significant information helpful to watershed managers and planners especially in crafting a plan for integrated watershed management wherein programs and projects implementation have to be prioritized.
R.C.C. Puno; G.R. Puno; B.A.M. Talisay
Abstract
Predicting the impact of land cover and climate change on hydrologic responses using modeling tools are essential in understanding the movement and pattern of hydrologic processes within the watershed. The paper provided potential implications of land conversions and climate change scenarios on the hydrologic ...
Read More
Predicting the impact of land cover and climate change on hydrologic responses using modeling tools are essential in understanding the movement and pattern of hydrologic processes within the watershed. The paper provided potential implications of land conversions and climate change scenarios on the hydrologic processes of Muleta watershed using soil and water assessment tool model. Model inputs used include interferometric synthetic aperture radar-digital elevation model, 2016 land cover map, soil map, meteorological and hydrologic data. The model was calibrated using appropriate statistical parameters (R2=0.80, NS=0.80 and RSR=0.45). Model validation using observed streamflow with the same statistical parameters (R2 = 0.79, NS = 0.67 and RSR = 0.57) showed that the result was statistically acceptable. The model provided potential implications of land conversions and climate change adversely affecting hydrologic processes of critical watersheds. Climate change projections with a 13% decrease in rainfall directly influenced the decrease in hydrologic processes. Meanwhile, urbanization had influenced the increase in surface runoff, evapotranspiration, and baseflow. The increase of forest vegetation resulted in a minimal decrease in baseflow and surface runoff. The watershed hydrologic processes were influenced by changes in land cover and climate. Results of this study are useful by the localities and policy makers in coming up with a more informed decision relative to the issues and concern on hydrological responses in the uplands.
S.M. Tajbakhsh; H. Memarian; M. Sobhani; A.H. Aghakhani Afshar
Abstract
Hydrologic modeling of semi-arid watersheds is imperative for the development of appropriate water and soil conservation plans. In the current study, the efficiency of Kinematic Runoff and Erosion model-version 2 (K2) model was used to evaluate water discharge and sediment load simulation of Bar watershed, ...
Read More
Hydrologic modeling of semi-arid watersheds is imperative for the development of appropriate water and soil conservation plans. In the current study, the efficiency of Kinematic Runoff and Erosion model-version 2 (K2) model was used to evaluate water discharge and sediment load simulation of Bar watershed, located in the north-eastern part of Iran. The K2 model relies on the kinematic wave approach to route surface flow. The drainage network and planes are discretized to represent the watershed. In order to evaluate the model, 3 and 2 reported rainfall incidents in various dates were selected for K2 calibration and validation, respectively. The multiplier approach was employed for model calibration. The results of sensitivity investigation revealed that the soil parameters Ks-CH, n and G had the highest impact on flow discharge. Through the calibration process, the Nash-Sutcliff Efficiency and the coefficient of determination as fitting metrics for water discharge simulation (based on event #2, dated 16 March 1992) were estimated to be 0.78 and 0.88, respectively. According to the aggregated measure, the highest K2 efficiency was obtained during the calibration process based on event #2. Other storm events were resulted in a good simulation, as well. During the validation process, K2 simulation (based on event #4, dated 07 March 1991) led to the Nash-Sutcliffe Efficiency and R2 of 0.77 and 0.71, respectively. The K2 calibration for sediment load simulation was performed through the alterations of the Pave and Rainsplash parameters. The bias percentages between simulated and observed total sediment loads based on events #2 and #4 were 5% and 16%, respectively. Conclusively, the K2 model showed an acceptable robustness in the hydrological simulation of Bar watershed as a representative semi-arid watershed in northeast of Iran.
S. Noorabadi; A.H. Nazemi; A.A. Sadraddini; R. Delirhasannia
Abstract
There is a close connection between saltwater intrusion into aquifers and groundwater extraction. Freshwater extraction in coastal aquifers is one of the most important reasons for the saltwater intrusion into these aquifers. Condition of extraction system such as well depth, discharge rate, saltwater ...
Read More
There is a close connection between saltwater intrusion into aquifers and groundwater extraction. Freshwater extraction in coastal aquifers is one of the most important reasons for the saltwater intrusion into these aquifers. Condition of extraction system such as well depth, discharge rate, saltwater concentration and etc. could affect this process widely. Thus, investigating different extraction conditions comprises many management advantages. In the present study, the effects of freshwater extraction on saltwater interface displacement have been investigated in a laboratory box. Three different well depths (H) were considered with combinations of 3 different extraction rates (Q) and 3 saltwater concentrations (C) for detailed investigation of the effects of these factors variations on saltwater displacement. SEAWAT model has been used to simulate all the scenarios to numerically study of the process. The experimental and numerical results showed that when the C and Q rates were small and the well depth was shallow, the saltwater interface wouldn’t reach the extraction well, so the extracted water remained uncontaminated. When the C and Q rates were increased and the well was deepened, the salinity of the extracted water became higher. When the Q and C rates were high enough, in the shallow well depth, the final concentration of the extracted water was low but a huge part of the porous media was contaminated by the saltwater, furthermore when the well was deepened enough, the final concentration of the extracted water was increased but a small part of the porous media was contaminated by the saltwater. Finally, the results showed that when the Q and H rates were high enough, the extraction well behaved like a barrier and didn’t allow the advancing saltwater wedge toe to be intruded beyond the wells.
M. Eshghizadeh; A. Talebi; M.T. Dastorani; H.R. Azimzadeh
Abstract
Erosion plots were selected for characterizing the effects of main natural factors on runoff and soil loss in a semi-arid region. These erosion plots with an area of 40 m2 are located in the Kakhk experimental watershed in Gonabad County of Khorasan-e Razave Province in the north-eastern Iran. Data acquired ...
Read More
Erosion plots were selected for characterizing the effects of main natural factors on runoff and soil loss in a semi-arid region. These erosion plots with an area of 40 m2 are located in the Kakhk experimental watershed in Gonabad County of Khorasan-e Razave Province in the north-eastern Iran. Data acquired from 2008 to 2015 include slope, aspect, soil texture and land covers (canopy and litter) factors that were selected as main natural factors and it was tried to determine the effects of these factors on runoff and soil loss amount. In the next stage, it was focused on evaluation of the effects of land covers on runoff generation and soil loss in more details. For this purpose, in each class of the mentioned factors, the relationship between land covers and runoff and soil loss was analysed. The maximum of runoff and soil loss were occurred at E site with the amount of 15.6 mm and 140 g/m2 respectively. Results showed that soil loss and runoff have decreased where the amounts of land covers have increased, and the line gradient is steeper for soil loss reduction than runoff generation. The result especially characterized the role of land covers on soil loss. Based on these results land covers have a significant effect on soil loss but this effect is mostly highlighted in the highest and lowest conditions of erosion potential, rather than the medium erosion potential condition. Furthermore, in each plot and event, a dominant factor determines the quantity of the effect of land cover on runoff and soil loss.
S. Sharma; R.C. Chhipa
Abstract
Water is a unique natural resource among all sources available on earth. It plays an important role in economic development and the general well-being of the country. This study aimed at using the application of water quality index in evaluating the ground water quality innorth-east area of Jaipur in ...
Read More
Water is a unique natural resource among all sources available on earth. It plays an important role in economic development and the general well-being of the country. This study aimed at using the application of water quality index in evaluating the ground water quality innorth-east area of Jaipur in pre and post monsoon for public usage. Total eleven physico–chemical characteristics; total dissolved solids, total hardness,chloride, nitrate, electrical conductance, sodium, fluorideand potassium, pH, turbidity, temperature) were analyzed and observed values were compared with standard values recommended by Indian standard and World Health Organization. Most of parameter show higher value than permissible limit in pre and post monsoon. Water quality index study showed that drinking water in Amer (221.58,277.70), Lalawas (362.74,396.67), Jaisinghpura area (286.00,273.78) were found to be highly contaminated due to high value of total dissolved solids, electrical conductance, total hardness, chloride, nitrate and sodium.Saipura (122.52, 131.00), Naila (120.25, 239.86), Galta (160.9, 204.1) were found to be moderately contaminated for both monsoons. People dependent on this water may prone to health hazard. Therefore some effective measures are urgently required to enhance the quality of water in these areas.