In arid and semi-arid regions, water harvesting systems can augment water supply for crop production purposes. The functioning of this type of system is controlled by three major factors: weather, crop and soil characteristics. In particular, the weather factors vary stochastiscally and thus, need to be predicted on the basis of their probability of occurrence. Furthermore, long-term historical data is scarce in the arid regions. Consequently, the simulation approach is a good alternative for designing the system. This study developed a micro-computer based model, SSWHS89.BAS, for design of small scale water harvesting systems for perennial crops. The model uses elements of a simulation computer program, CLIMATE.BAS (Woolhiser, 1988), to generate daily rainfall, maximum and minimum temperature and radiation data and predicts evapotranspiration and runoff data from a deterministic computer program, PENMNSCS.BAS for the location of interest. The model was used to determine the characteristics of a water harvesting system in a vineyard field at Sonoita, Az.

A simple water balance model was applied to a micro-catchment water harvesting system for a semi-arid area in the North-Eastern part of Jordan. Two Negarim micro-catchment water harvesting systems were built at Al-Khanasri research station. A Randomized complete block design (RCBD) in factorial combination was used with six treatments and three replicates. Each plot was divided into two parts; a runoff area, and a run-on area. Two different treatments were used for the catchment area, these were: compacted (T1) and Natural treatments (T2). Three treatments were used for the run-on area, these were: disturbed (S1), stones (S2), and crop residue mulch (S3). Soil water content was measured over a depth of 0-1 m during the seasons 96-97 in these micro-catchments. In this model; daily rainfall, runoff, and evaporation were used. Runoff was calculated by the curve number method; evaporation was calculated by the Penman equation, the Priestley and Taylor method and the Class A pan approach. The least squares method was used for optimizing model parameters. The performance of the model was assessed by different criteria, such as root mean square error, relative root mean square error, coefficient of determination and the Nash-Sutcliffe efficiency method. The performance of the micro-catchments system was also evaluated. Results showed that with limited but reliable hydrological data good agreement between predicted and observed values could be obtained. The ratio of water storage in a one meter soil depth to the rainfall falling on each catchment indicated that T1S2 and T1S3 have the highest values in size1 plots while T2S1 and T2S2 have the highest values in size 2 plots. Modelling results showed that for all the size 1 plots, the required ratio of the cultivated to catchment area, (C/CA), required to ensure sufficient harvested water, was less than the actual ratio used in the experimental design. For the size 2 plots this was only true for the T1 treatments. Consequently for the majority of plot sizes and treatments, the results showed that a smaller catchment area is capable of providing sufficient harvested water to meet crop growth requirements. The experimental ratio was based on a typical yearly design rainfall for the region having either a 50% or 67% probability of occurrence. Results also indicated that using stones and crop residue as mulch on the soil surface in the cultivated area was effective in decreasing the evaporation rate. S3 was more efficient than S2 as it stored more water due to the higher infiltration rate (12.4 cm/hr) when compared to S2 (4.1 cm/hr).

Thesis (M.Dev.) --University of Limpopo, 2011 / Food security in most drought-stricken areas of Limpopo Province is a challenge to the Department of Agriculture and to all the people living in the province, especially to the resource poor smallholder farmers. Finding remedial solutions to agricultural production in stress prone conditions is therefore a high priority. The introduction of Challenge Programme Water for Food (CPWF) technologies/techniques to smallholder dry land farming in Greater Giyani Municipality was seen as one of the solutions. However, there are constraints raised by CPWF technology adopters such as shortage of labour, lack of ploughing equipment, lack of credit, shortage of land and marketing. CPWF technologies are suitable for smallholder dry land farming, especially rainwater harvesting technologies. Smallholder farmers need to be remobilised and trained on the potential benefits of CPWF technologies to enhance their adoption and spread to other areas.

Sustainable Built Environments Senior Capstone Project / Across the world, populations continue to grow while water supplies stay fixed. In the American Southwest, water supplies are at an all time low, yet warm, favorable conditions continue to lure residents to the area. With some of the country’s lowest fresh water reserves, it is imperative that changes are made to water usage trends and associated energy inefficiencies. An analysis of water usage in Tucson was conducted to evaluate potential solutions for reducing consumption and to correspondingly shrink energy usage. Case studies were investigated, census numbers were used to roughly calculate statistics, existing knowledge on water conservation techniques were researched, and alternative water filtration as well as distribution systems were scrutinized for their viability amongst current infrastructure. The potential to reduce water usage is greatest with the largest user of water in Tucson, the single-family residence. On average the single-family residence is capable of effectively saving nearly 25,000 gallons of water per year with efficient fixtures, another 25,000 gallons per year by reducing outdoor water use by half, and another 10,625 gallons by utilizing rainwater harvesting. Combine those savings and multiply them by the 225,000-240,000 single-family residents estimated to be in Tucson and the savings reach more than five billion gallons a year, effectively almost cutting water consumption in Tucson by a fifth. Further, to keep remaining usage impacts negligible, implementation of an indirect or direct potable water reuse system could satisfy populations for decades by reusing water that would normally be discarded as effluent. Water consumption must be curved so that it can satisfy a growing population’s needs. Amongst residents of Tucson, single-family residences have the greatest potential to reduce water and associated energy needs. Through conservation techniques, water harvesting, reducing outdoor water usage, and potable reuse, limited water supplies can satisfy future generations to come.

Khartoum State in Sudan is subject to the erratic and intense rainfall during the short rainy season and dryness and heat throughout the rest of the year. High intensity rainstorms with a short duration have become more frequent in the area during the last two decades resulting in cities inundation and flash floods in the rural parts. On the other hand, the dry season means hot weather in the urban parts and water shortage in the rural part. Rural areas are dependent on the runoff water brought about by the seasonal streams as a source of water. For this study, Khartoum City Center and Seleit area were taken to investigate the application of water harvesting in the urban and rural areas, respectively. Accordingly, the hydrological characteristics and the specification of the potential water harvesting sites and systems were examined. For Khartoum City Center, characteristics of the drainage system were examined using ArcGIS platform. It is found that the drainage system covers 42% of the area with total capacity of 24000 m3. Daily rainfall data for urban meteorological station were used to calculate the probability and the return period of the rainfall, as well as the potential runoff. Rainfall probability of occurrence was calculated applying Gumbel distribution method for extreme events that were arranged according to the Peak-over-Threshold method. The potential runoff that could be generated from a certain rainfall was calculated using the Natural Resources Conservation Services method provided by the United States Department of Agriculture (US-NRCS). Accordingly, the curve number was calculated depending on the land use/land cover and the hydrological soil group. Consequently, the weighted curve number is found to be 94%, indicating dominant imperviousness. 13.1 mm rainfall depth produces runoff volume equal to the drainage system capacity with return period of one year; whereas more than four folds the drainage system capacity is produced by 30 mm rainfall depth that is considered the threshold for raising flood hazard. Six potential sites for roof rainwater harvesting were selected. Accordingly, it is found that, the application of roof water harvesting in 18% and 72% of the commercial and business district buildings can accommodate the runoff resulting from the 13.1 and 30 mm rainfall depth, respectively. Hence, impounding rainstorm water would help managing the urban runoff water, and consequently, the stored water could be used for making more green areas that will enhance the urban environment. Three watersheds of ephemeral streams (wadi), namely Wadi El Kangar, Wadi El Seleit, and Wadi El Kabbashi make up Seleit area. Distinct maps were prepared in ArcMap for the calculation of the potential runoff and the specification of the appropriate water harvesting sites and systems. The Wadis watersheds areas are found to be 540, 344 and 42 km2 for Wadi El Kangar, Wadi El Seleit and Wadi El Kabbashi, respectively. Daily rainfall data of rural meteorological station were classified into three groups representing the soil dry (AMCI), moderate (AMCII), and wet (AMCIII) moisture conditions; the respective CNI, CNII, and CNIII values were calculated accordingly. The weighted CN values indicate high runoff potential within the three soil moisture conditions. Accordingly, the rainfall thresholds for runoff generation for AMCI, AMCII and AMCIII conditions are found to be respectively 18.3 mm, 9.1 mm and 4.4 mm for Wadi El Kabbashi and 22 mm, 11 mm and 5 mm for both Wadi El Seleit and Wadi El Kangar. El Kangar dam subwatershed was used for calibrating the potential runoff calculated by the NRCS method. Since the Wadis are ungauged, Google Earth and GIS platforms were used to calculate geometrically the volume of the dam reservoir water for three years. This volume was compared to the annual runoff calculated by the NRCS method. Consideration to different factors was made to locate the potential water harvesting sites. Accordingly, water harvesting systems for fodder and crop plantation; sand storage surface or subsurface dams; or groundwater recharge, were specified. The socio-economic study revealed that the financial capacity, if any, of the villagers is very limited. Thus, the financial source for the construction of the suggested potential water harvesting or the rehabilitation of the existing ones is questionable. Hence, other potential financial sources are needed to help executing water harvesting projects in the region, e.g. Khartoum State Government. Applying water harvesting in Seleit area is found to be promising. Improving the livelihood of the villagers by applying runoff water harvesting could assure better water accessibility, better income generation from farms production, and allocation of time for other activities, e.g. education. This would be reflected in reduced migration to nearby cities and stabilized market supply of agricultural and animal products. Therefore, the development of the rural part is of great benefit to the development of Khartoum State, as long as the interdependency and mutual benefit between the rural and urban areas, represented by the local food and labor market, remain exist.

Thesis (M Eng) -- University of South Australia, 1993

Thesis (M Eng) -- University of South Australia, 1993

Thesis (M. S.)--Architecture, Georgia Institute of Technology, 2009. / Committee Chair: Dagenhart, Richard; Committee Member: Elliott, Michael; Committee Member: Green, David

M.Ing. (Civil Engineering Science) / In recent years, there has been an international trend towards installing rainwater tanks in an attempt to save water. However, there are no clear guidelines for determining the optimal size of such a tank in South Africa. This study investigates the possibility of simplifying the process of sizing a rainwater tank for optimal results. It utilises daily data from four rainfall stations, namely Kimberley, Mossel Bay, Punda Maria and Rustenburg, obtained from the South African Weather Services. The water use is considered to be for indoor purposes only, therefore assuming a constant daily demand to be extracted from the tank. The required size of a rainwater tank is influenced by the MAP, the area of the roof draining into the tank, the water demand (both the average demand and seasonal variations), the desired reliability of supply, and the rainfall patterns. The first step in simplifying the process is to consolidate the above variables. The tank volume is expressed as the number of days it could supply the average daily water demand. Another variable is created which provides the ratio of the total water volume which could theoretically be harvested from the roof in an average year, to the total water demand, from the tank, for a year. This has the effect of consolidating the MAP, the roof area, the water demand and the tank volume into two variables only and eliminates the need to consider numerous demand values. Using simulations over 16 years for each location, the relationships between these variables were determined to ensure 90%, 95% and 98% assurance of supply.

Khartoum State in Sudan is subject to the erratic and intense rainfall during the short rainy season and dryness and heat throughout the rest of the year. High intensity rainstorms with a short duration have become more frequent in the area during the last two decades resulting in cities inundation and flash floods in the rural parts. On the other hand, the dry season means hot weather in the urban parts and water shortage in the rural part. Rural areas are dependent on the runoff water brought about by the seasonal streams as a source of water. For this study, Khartoum City Center and Seleit area were taken to investigate the application of water harvesting in the urban and rural areas, respectively. Accordingly, the hydrological characteristics and the specification of the potential water harvesting sites and systems were examined. For Khartoum City Center, characteristics of the drainage system were examined using ArcGIS platform. It is found that the drainage system covers 42% of the area with total capacity of 24000 m3. Daily rainfall data for urban meteorological station were used to calculate the probability and the return period of the rainfall, as well as the potential runoff. Rainfall probability of occurrence was calculated applying Gumbel distribution method for extreme events that were arranged according to the Peak-over-Threshold method. The potential runoff that could be generated from a certain rainfall was calculated using the Natural Resources Conservation Services method provided by the United States Department of Agriculture (US-NRCS). Accordingly, the curve number was calculated depending on the land use/land cover and the hydrological soil group. Consequently, the weighted curve number is found to be 94%, indicating dominant imperviousness. 13.1 mm rainfall depth produces runoff volume equal to the drainage system capacity with return period of one year; whereas more than four folds the drainage system capacity is produced by 30 mm rainfall depth that is considered the threshold for raising flood hazard. Six potential sites for roof rainwater harvesting were selected. Accordingly, it is found that, the application of roof water harvesting in 18% and 72% of the commercial and business district buildings can accommodate the runoff resulting from the 13.1 and 30 mm rainfall depth, respectively. Hence, impounding rainstorm water would help managing the urban runoff water, and consequently, the stored water could be used for making more green areas that will enhance the urban environment. Three watersheds of ephemeral streams (wadi), namely Wadi El Kangar, Wadi El Seleit, and Wadi El Kabbashi make up Seleit area. Distinct maps were prepared in ArcMap for the calculation of the potential runoff and the specification of the appropriate water harvesting sites and systems. The Wadis watersheds areas are found to be 540, 344 and 42 km2 for Wadi El Kangar, Wadi El Seleit and Wadi El Kabbashi, respectively. Daily rainfall data of rural meteorological station were classified into three groups representing the soil dry (AMCI), moderate (AMCII), and wet (AMCIII) moisture conditions; the respective CNI, CNII, and CNIII values were calculated accordingly. The weighted CN values indicate high runoff potential within the three soil moisture conditions. Accordingly, the rainfall thresholds for runoff generation for AMCI, AMCII and AMCIII conditions are found to be respectively 18.3 mm, 9.1 mm and 4.4 mm for Wadi El Kabbashi and 22 mm, 11 mm and 5 mm for both Wadi El Seleit and Wadi El Kangar. El Kangar dam subwatershed was used for calibrating the potential runoff calculated by the NRCS method. Since the Wadis are ungauged, Google Earth and GIS platforms were used to calculate geometrically the volume of the dam reservoir water for three years. This volume was compared to the annual runoff calculated by the NRCS method. Consideration to different factors was made to locate the potential water harvesting sites. Accordingly, water harvesting systems for fodder and crop plantation; sand storage surface or subsurface dams; or groundwater recharge, were specified. The socio-economic study revealed that the financial capacity, if any, of the villagers is very limited. Thus, the financial source for the construction of the suggested potential water harvesting or the rehabilitation of the existing ones is questionable. Hence, other potential financial sources are needed to help executing water harvesting projects in the region, e.g. Khartoum State Government. Applying water harvesting in Seleit area is found to be promising. Improving the livelihood of the villagers by applying runoff water harvesting could assure better water accessibility, better income generation from farms production, and allocation of time for other activities, e.g. education. This would be reflected in reduced migration to nearby cities and stabilized market supply of agricultural and animal products. Therefore, the development of the rural part is of great benefit to the development of Khartoum State, as long as the interdependency and mutual benefit between the rural and urban areas, represented by the local food and labor market, remain exist.