Journal of Water Harvesting Research
Volume:4 Issue: 1, Winter and Spring 2021

Due to the climate change the efficient use of fresh water has become a hot issue. One of the ways to collect water that could otherwise be wasted, is the water harvesting technique. These techniques have been known for centuries and widely applied in the Middle East. This paper presents a simple and easy-to-use water-balance based rainwater harvesting model called WHCatch. It has been designed to investigate the effects of water harvesting on the catchment scale. The catchment is divided into several sub-catchments which can store water for the purpose of water harvesting. The model has been created as a simple Excel workbook with some VBA-code for the computations. Results are presented in the same workbook as separate worksheets. Graphical presentations are created automatically. The capabilities of the workbook are presented and examples of in- and output are shown. Due to its flexibility, the model is suitable to show the effects of climate change as well. It is especially suitable to visualize the effects of measures.

Due to increasing population growth, inadequate management of surface and subsurface water resources, and the escalation of the water crisis in the coming years, will be inevitable. Therefore, it is necessary to provide scientific and multi-criteria indices capable of more precisely examining the status of surface and subsurface water resources. In this study, the water poverty index (WPI) based on five weighted components of resources, availability, capacity, consumption and environment of the Fasa plain during 2008-2018 were calculated and their trends were evaluated using parametric and nonparametric statistical tests (i.e. Mann-Kendall and Spearman). The results showed that the consumption component (0.47) and the capacity component had highest and lowest role in the WPI index. Trend analysis of the WPI index showed that the WPI based on the linear regression, Mann-Kendall and Spearman tests had a non- significant decreasing trend (with S= -0.01, ZS= -1.03 and ZD= -1.38, respectively). It is natural that the decrease in WPI values ​​reflects an increase in the level of crisis in available water resources. Due to the downward trend of WPI index in the Fasa plain, proper scientific and practical management of water resources is essential to provide the enable long-term sustainable use of resources.

Climate change impacts are very dependent on regional geographic features, local climate variability and socio-economic status. Therefore, impact assessment researches on climate change must be launched at the local or at the regional level so that the evaluation of consequences can take place. Climate scenarios are produced by Global Circulation Models for the entire Globe with spatial resolutions of several hundred kilometers. For this reason, downscaling methods are used to bridge the gap between the large-scale climate scenarios and the fine scale where local impacts happen. In order to overcome limited computing power and for catchments with limited data, statistical downscaling is the most feasible approach in obtaining climate data for future impact investigations. So a decision support model named SDSM was used to downscale the data. Model errors and uncertainties were estimated using non-parametric statistical methods at the 95% confidence interval for precipitation, maximum temperature and minimum temperature for the mean and variance for a single site in Kermanshah in the western part of Iran. The comparison between the observed dataset and the simulations showed that the SDSM model was able to better represent the minimum and maximum temperature while for precipitation simulations are slightly under-estimated but still acceptable according to statistical tools. It is also presented simulations for the A2 SRES scenario for the 2041-2069 periods showing that the method can produce similar general tendencies.

Ancient Iranian civilization flourished in an arid and desertic landscape for thousands of years merely due to special water harvesting and management systems. However, currently the country faces a challenging water resources crisis. Since perception of importance of a subject or technology is key factor in its adoption, this study attempts to inquire into perception of Iranian citizens on the importance and necessity of rainwater harvesting. Therefore, 187 respondents from six regional capital cities were interviewed on their RWH experience, knowledge and opinions on the significance and benefits of RWA. The face-to-face questionnaire administration mode was used for the survey. Results indicates that there is a low level of RWH experience and knowledge among the current generation of Iranian, whereas more than 70 and 40% have no RWH experience and information. Respectively. However, there is a high inclination (80%) towards RWH adoption provided that financial supports shall be available. Since more than 51% of the respondents perceive RWH is highly and very highly necessary in large public and commercial buildings, RWH should start from these buildings. More than half of the respondents believe that rainwater is useful for domestic water supply. The respondents perceive that the reduction of water bills (30% of respondents) and alleviation of water shortage crisis (55% of respondents) are the most important advantages of RWH for private households and general public, respectively. More than one-third of the respondents conceive that main beneficiary of RWH will be agriculture sector

Fruit trees are grown in arid environments under irrigation. In most of the dry environments, irrigation water is not available or is scarce during the growing season; therefore, irrigation may not be possible or feasible. Yet farmers continue to grow trees under this dry rainfed condition. Low precipitation and the occurrence of frequent drought spells stress trees and cause low yields or crop failure. Farmers, to avoid crop failure, supplement rainwater with costly irrigation water often transported to the sites by tankers. Through rainwater harvesting, precipitation is concentrated through runoff from larger catchments to the basins of trees to be stored in the root zone for using during the dry period. It is however important to evaluate the capacity of system and its design parameters to ensure sufficient and efficient water supply for individual trees over the drought periods. Field trials for almond orchards were conducted over 7 years in a dry area in Northwestern Iran with mean annual rainfall 250 mm. The objective is to evaluate the impact of a range of micro-catchment rainwater harvesting practices and soil amendments on the performance of two varieties of almond trees widely grown in the area. Treatments include catchment size and geometry, surface treatment, soil water absorbent and fermented manure. Results showed that a 49 m2 compacted catchment is sufficient to generate enough runoff to supplement rainfall for each almond tree with no effect of catchment geometry. The addition of a super absorbent material to increase soil-water storage of the root zone did not outperform the use of fermented manure. Threshold rainfall for initiation of runoff ranged from 3.5 to 5.5 mm. In a 7 mm rainfall event and basin size of 49 m2, the runoff coefficients ranged from 13.1, to 48.4 percent. At maturity, almond trees yielded 612 kg dry nuts/ha using water-harvesting system where no irrigation was needed. In this dryland environment, farmers can grow economical rainfed almond orchards with appropriate micro catchment rainwater harvesting system.

In order to efficiently manage groundwater resources, determination of the main sampling points is very important to reduce sample size and save time and cost. Principal Component Analysis (PCA) is one of the data reduction techniques that has an important role in identifying insignificant data. In this research, 22 wells of Gonabad plain with a statistical length of 10 years (2007-2016) were used. In the studied area, the annual average of 11 quality parameters of Ca, Mg, Na, EC, TDS, Cl, SAR, HCO3, SO4, TH, pH groundwater was investigated by using this technique to determine the quality effective wells in the aquifer of this plain. Using PCA, the relative importance of each well was calculated between 0 (for completely ineffective well) to 1 (for the very effective wells). The results showed that among the 22 wells in the study area, 7 wells were identified as the quality effective wells of Gonabad plain, which had a good dispersion in the region and could play an important role in reducing sampling costs.

Rainwater harvesting system is one of the approaches to an adaptation to climate change and global warming. Rainwater harvesting has been resulted in diversification of water resources and will lead to increase water security. Optimum utilization of rainfall in arid and semi-arid plains ranging in sloping surfaces is very important. In areas where rainfall distribution during the season is not commensurate with the water needs of trees and plants, the water harvesting system and sand filters installed at the end of the system can lead to water infiltration into the rhizosphere of plant roots. The aim of this project is to investigate the performance levels of insulation, semi-insulating, and natural (With or without gravelly filters) range land to expansion of water supply around the seedlings dry almond in Isfahan province. To do this, 48 plots with dimensions of 7 * 4 meter with three treatments of insulation coating, semi-insulation, and natural cover with gravel filters and without gravel, filters were constructed at the end of rainwater level systems in three replications on the slope with a slope of 18%. At the bottom of each plot, a soil profile with dimensions of 1 * 1 * 1 meter was created to dig a seedling-planting hole with the aim of increasing the soil moisture. At this stage, materials such as rotten manure and straw, as well as nylon coating were used to increase water penetration and more moisture retention in the soil. In order to investigate the effect of the mentioned factors in increasing soil moisture, almond seedlings were planted in the system and simultaneous data on plant growth and soil moisture were recorded at two depths of 30 and 50 cm. Changes in pit moisture were measured at specific time intervals and finally statistically analyzed. Statistical analysis showed that among the treatments used, the treatment of adding 25% by volume of soil of seedling planting hole with rotten manure plus straw and straw and nylon with insulation cover and gravelly filter had the maximum volumetric moisture at a depth of 50 cm.

Drought is a hazardous phenomenon, as a result of climatic parameters abnormalities. The effects of high and low drought occur in different parts of the country, and its effects are more noticeable in arid and semi-arid regions. One of these areas is western Iran, which has been affected by this phenomenon in recent years. The purpose of this study is drought modelling and investigation in western Iran. To do this, climatic parameters were first used, including precipitation, temperature, sunshine, relative humidity and wind speed in 32 years (1987-2018) at 16 stations in western Iran. For modelling the TIBI fuzzy index, at first, four indices (SET, SPI, SEB, MCZI) were been fuzzy in Matlab software, then the indices were compared and finally, by Vikor multivariate decision-making model was used to prioritize areas affected by drought. The results of this study showed that the impact of rainfall on the drought intensity on the 12-months scale is weaker than the 6-months scale. In the six months, from May 1998 to August 2006, the trend was increasing and then followed the steady pattern, but on a 12-month scale, from August 1995 to December 2001, the trend was increasing and after this month it followed the mostly steady pattern. The highest frequency of drought at 6 and 12-month scale occurred in Ilam station and its lowest was in Sarpule-Zahab station. The T.I.B.I index accurately reflects the four indicators of SET, SPI, SEB and MCZI. Based on the modelling, T.I.B.I fuzzy index showed relative superiority to the SPEI fuzzy index. Finally, according to the Vikor multivariate decision-making method, the Ilam station with a score of 0.99 was more prone to drought occurrence.

It is necessary to study and analyze the frequency of extreme rainfall events to determine the best-fit distribution that can predict the occurrence of the certain natural phenomena such as rainfall, flood, etc. In this study assessed to determine the best-fit distribution, the frequency analysis of threshold rainfalls considering Coupled Model Intercomparison Project phase 5 General Circulation Models (CMIP5 GCMs) under two Representative Concentration Pathways (RCP) scenarios (2.6 and 8.5). For this purpose, four empirical formulas (Hazen, Weibull, Tukey, and Cunnane) were used to estimate the return periods of threshold precipitation. Also, various probabilistic distributions including normal distributions, log normal (LN), log normal 3 (LN3), Gumble, Pearson type 3 (P3), and log Pearson type 3 (LP3) were applied to predict the distribution of threshold rainfalls. Kolmogorov-Smirnov test was used to determine the best-fit probability distribution function (PDF). Results revealed that the Hazen formula obtained the most estimate in the period of observation and future periods, and the near future (2015-2040) and the far future periods (2041-2065). According to the results, the LN3, LP3 and GEV probabilistic distributions presented the best PDF for threshold rainfalls in most periods. Among the best-fit distributions, LN3 was received 45 percent and LP3 and GEV received 20 and 30 percent of the best result, respectively. These results indicate there are severe abnormalities in the threshold precipitations, especially in high amounts. The results of this study can be used to develop more accurate models against the dangers, and damages caused by Extreme weather and flood.

Valuable studies have been conducted in recent years to collect water from impermeable urban levels in some parts of the country. Nevertheless, the background of the studies in this field has been poor in south Khorasan province, Iran. This study aims to help urban planners and managers to recognize the potential of water harvesting. The purpose of this study is to identify and prioritize the sub-catchment covered by the rock outcrops playing an important role in runoff production. This work was carried out via the modeling of runoff by empirical methods and the SWMM model in Qaen urban watershed. Accordingly, it is possible to determine the amount of water available for supplemental irrigation of the urban green space and thereby provide a suitable extension pattern for similar areas. The irrigation in the urban park is done by well, which is a major problem for Qaen, as an arid area. About 54% (248.4 ha) of the basin surface has been populated by the 90% rock outcrops that has high runoff potential and can be useful in planning in terms of high potential of runoff production. Considering the existing facilities and the number of park trees, an approach is needed. The water shortage for supplemental irrigation of this park will compensate, if only 10% of the annual runoff equivalent to 11800 m3 can be harvested and stored during the months with no precipitation.

Three percent out of seventy percent of earth planet water is freshwater that one percent of that is accessible. Pollution is added to the water shortage crisis, so humans are thinking about new water resources and trying to obtain them. Rainfall in Gilan province is abundant but irregular, especially in Rasht city. Temperature and evaporation increase in the late spring and summer, also, rainfall decrease in that time. Meanwhile, all cities and villages of Gilan, especially Rasht and its suburbs, use the gas air conditioner, and using this cooling system in buildings is developing day by day. The research was carried out in a room with a square of 33 m2 at the temperature of comfort range of 20 °C using an air conditioner of the 28000 type. The water flow, temperature, and humidity were recorded hourly during the day and night, and statistical analysis (descriptive-analytical) was performed. Finally, a simple model was obtained from the existing relationship between climatic elements (temperature and humidity) with water flow. Temperature and water flow have a first-degree relationship and humidity and water flow have a second-degree relationship. The first-degree relationship showed that when the temperature decreases, the water flow increases so that a negative or inverse relationship is created. But in the second relation, with increasing humidity, Water flow increases, and with decreasing humidity, the flow decreases. Temperature as an independent and main factor has an inverse effect on water flow and humidity. Finally, the data (temperature, humidity, and water flow) were classified in SPSS software. By setting the temperature and humidity data in one of the groups, the amount of water obtained from the air conditioner (flow) is well predicted, and it can be generalized. The average amount of water obtained from the air conditioner is about 30 Lit/hr for an area of 33 m2. Using more air conditioners in more areas will obtain more water flow which will meet a big part of the needs of families.

Due to population growth and political development of Birjand city, the status of aquifer vulnerability is important for development. Studies on the DRASTIC index indicate the lack of consideration of land use status and the effect of pollutant transfer on aquifer vulnerability. DRASTIC-LU index has eight parameters and since the incoming weights to this index can be a matter of taste, the model was calibrated according to the Nitrate concentration in the wells of the region. The model was calibrated by using AHP method and the completion of questionnaires was analyzed from the point of view of the importance of each parameter in terms of weight and rank. Questionnaire analysis was performed by couple comparison method and using Expert choice software. The calibrated results indicate an increase in the correlation coefficient between the vulnerability index and the Nitrate concentration at the aquifer. The results showed that land use was positive due to the surface concentration of pollutants in the agricultural and urban sectors, which played an important role in the vulnerability index of aquifers. The results also showed that the accuracy of the vulnerability index could be increased by using the proposed method of this research and calibrate weights and ranks by using the hierarchical analysis method. The correlation between Nitrate concentration and DRASTIC-LU index in the aquifer had increased from 42% to 65%.