Journal of Water Harvesting Research
Volume:4 Issue: 2, Summer and Autumn 2021

In this study, copula functions and precipitation concentration index were used for the joint frequency analysis of the conditional probability of rainfall-rainfall and PCI-PCI at Birjand and Tabas meteorological stations in eastern Iran. Monthly rainfall data ​​in the statistical period 1969-2018 were considered in this regard. The results of PCI at the studied stations showed that at both stations the distribution of rainfall pattern is highly irregular, which was worse at Tabas meteorological station. By selecting the appropriate marginal distribution function and also confirming the correlation between rainfall- rainfall and PCI-PCI ​​at Tabas and Birjand meteorological stations, the Gumbel-Hougaard and Clayton copulas were selected for the pair variables, respectively. The results of conditional probability showed that with different probabilities, rainfall and PCI of each station can be estimated using the rainfall and PCI ​​of another station. For example, according to the presented curves, if the annual rainfall of Birjand meteorological station is 220 mm, with 80% probability, the annual rainfall of Tabas meteorological station will be about 110 mm. According to the presented curves and the use of copula functions in the joint analysis of the rainfall and rainfall pattern, it is possible to better water resources management and water harvesting in the region.

Awareness of drought interrelationships and hydrological response of watersheds is a prerequisite for optimal management of surface and groundwater resources. The aim of the present study was to compare the impact of drought on surface and subsurface waters in the Kaka-Reza basin. In this study, after controlling the data, a common period (1982-2017) for hydrometric and rainfall stations was considered. Then the standardized precipitation index (SPI) and the standardized discharge index (SDI) were calculated for the 1-, 3-, 6-, 9-, 18-, 12- and 24-month time steps. The base flow and the corresponding index were calculated by B-Flow Lyne and Hollick recursive digital filter. Then, the standardized base flow index (SBFI) was calculated by adapting the SPI method for the corresponding time steps. Finally, the relationships between SPI, SDI and SBFI were investigated and analyzed using correlation method. The results showed that the greatest effect of drought on groundwater for the 9- and 12-month time step with coefficient of determination 0.87, While the effect of drought on surface water for the corresponding time step has a coefficient of determination of about 0.4.

The appropriate water resources planning and management is very important due to the critical status of water all around the world and the ever-increasing need for water in each country. Over the past few decades, due to the climate changes and the weakness of integrated water resources management and neglecting the country's sustainable development, the water resources in Iran has been faced great challenges. The main purpose of this study is to examine the impact of climate changes on supply to demands in various sectors of agriculture, urban, and industry in four regions downstream of the ALAVIAN dam, Maragheh, Iran. For this purpose, the LARS-WG model was calibrated to create the future data for the Maragheh synoptic station. Then, among the 14 GCM models in the LARS-WG model, the IPSLCM 4 model under the A1B scenario was selected as the most suitable model for the climate simulation of the study area by using R2, MAE and RMSE indices. In the next step, WEAP model was run for producing a reference scenario and providing information on climate changes in the future. The maximum and minimum annual temperatures during the years 2020-2040 is accompanied by an increase of about 1 ᵒC. In other words, the region climate is moving towards increasing in the temperature. The changes in monthly precipitation did not show a general increasing or decreasing trend. The results of this study also showed that the negative effects of climate change may intensify the tensions and water scarcity with an increase in exploitation of groundwater resources. The results showed as the water resources in the study area is assigned to the urban, industrial and agricultural sectors, the needs for the urban and industrial sectors at the future are completely met and water resource indices did not change under the effect of climate change. While the agricultural sector may encounter to water scarcity and may be damaged by climate changes, as compared with urban and industrial sectors.

Determining the runoff threshold is a prerequisite for more accurate flood estimates, design and estimation of flood production potential, and knowing its extent can lead to optimal water resource management of watersheds. In this study, using the mean annual rainfall, a map of homogeneous climatic regions of Iran was prepared. Then, at least 30 stations with common statistical period in each homogeneous region were selected. Using a topographic map with a scale of 1: 50,000 and determining the location of the stations, the study area and each of the sub-watersheds were identified and the basic parameters of the watershed were extracted using the GIS. Runoff threshold was simulated using AWBM rainfall-runoff model and after calibration and obtaining optimal model parameters. Watershed zoning was performed based on the values ​​obtained from the model and the percentage of surface cover of the watersheds was calculated according to the amount of runoff threshold for different climatic regions. The results showed that in all three climatic zones, almost half of the watersheds have runoff thresholds in a range of 0-5 mm and have the potential to convert rainfall into runoff and flood production. Watersheds with runoff threshold class (0-5 mm) were mainly located in the northern and central parts of West Azerbaijan province, north and northeast of Kerman province, and the northern and southern parts of Khuzestan province.

Iran has geographically located in an arid and semi-arid climate in most regions. Precipitation and its distribution in such regions cause irreparable damage by creating seasonal floods. This study presents a suitable model for optimizing watershed management and flood control in order to reduce flood risks. To reach to this purpose, the concept of time-area diagram in HEC-HMS hydrological model as well Single Successive Sub-watershed Elimination (SSSE) is employed to simulate the flood hydrograph corresponding to the design precipitation for each sub-watershed. According to SCS model for estimating flood discharge and kinematic wave for flood routing, the curve number and Manning's roughness coefficient were calibrated and identified as the most effective parameters. After evaluating the different search methods and objective functions, the univariate gradient as best search method and the Nash-Sutcliffe as the best objective function was selected due to the highest consistency of the simulated discharge in the three events. Finally, the model was validated for 2 storms and the Nash-Sutcliffe values ​​were calculated as 0.948 and 0.892, respectively. After calculating the peak discharge of each sub-watershed, the effect of each on the output flood production was determined using F and f flood indices. Then, isochronic surfaces of the watershed were extracted using three methods and the spatial distribution of the sub-watersheds in the area was investigated. The results revealed that the level of 0.75-1 located in the middle part of the watershed is posed as the first priority. Also, it is colcluded that the surfaces near the outlet have played a much smaller role in peak discharge. In general, from the outlet to the upstream and middle parts of the watershed, as travel time level increases, the effect of sub-watersheds on peak flow discharge increases.

One of the climate change impacts is an increase in the severe drought frequencies. Recently, low flow frequency analysis has been considered in the study of hydrological drought. This study aims to forecast low flow by 2099 in the Kan River Basin in order to assess climate change impacts on low flow in this region. For this purpose, temperature and precipitation data were simulated by HadCM3 model using SDSM downscaling model under the scenarios A2 and B2 by 2099. Runoff simulation was estimated using SWAT while calibration and validation were implemented using the SWAT-CUP software and SUFI-2 algorithm. The optimal parameters obtained from monthly and daily calibration were projected via SUFI-2 algorithm. The results showed an increase in temperature but decrease in precipitation rate, which in the most pessimistic scenario, proves an increase in maximum temperature up to 4.2 °C and for the precipitation, a decrease down to 10.8% by 2099 is expected, as well. Furthermore, the accuracy analysis of the simulated runoff based on the monthly and daily calibration results showed a good fit between observed and simulated values. In fact, their correlation coefficient with the measured values differed less than 0.03. Meanwhile for maximum flow values, daily calibration led to a more accuracy. The results of runoff forecasts showed a decrease in runoff, which is expected for spring and summer however an increase would be for autumn and winter. Overall, a 15 to 21 percent reduction in runoff was projected by 2099.

In dry regions the reuse of treated wastewater plays a significant role in management, operation, scheduling and utilization of water resources. In design and operate of the sewage treatment plants , it is essential to measure and forecast the harvested water from wastewater plants and balance the groundwater depletion with these new resources. In this study, potential water harvested by local wastewater treatment plants, Rotating Biological Contactor (RBC) is determined and balanced with water requirement of plants. Based on the design basis of RBC, the production ratio of 80 % is used and the produced discharge ranges from 4 up to 8 liter per seconds, with 140000 cubic meters per year. To quantify the balancing between RBC produced water and irrigation water requirements, a plant-by-plant water requirement is calculated and the operation rule of groundwater wells in the case study are determined and proposed as an action plan to the operator of wells.  Based on the results it was observed that the RBC can supply two times of pistachio orchard (23 hectares) irrigation requirements or 70 percent of the landscape and green space water needs in the case study.

The need to provide food for farms and the lack of roads and cars for transportation in the past led to the invention and innovation of a check dam called Bandar. Bandsar as a watershed check dam is the most important rain fed lands in semi-arid climates (such as South Khorasan Province). This structure turns threats (season flooding) into opportunities. Bandsar is a traditional structure with several main goals such as: cultivation, flood mitigation and erosion control, water harvesting and infiltration, flood water spreading and groundwater recharge. Accordingly, in this research detected 435 Bandsar with 205 thousand cubic meter by using satellite images and  field measurement , finally investigating the role of Bandsar in the floods hydrographic characteristics, water harvesting and infiltration of water resources in Seyujan-Tejk plain of Khosf city in South Khorasan province. For this goal, using climate data (1982-2020 period), topography map, cover plant, land use and features and capabilities of ArcGIS10.4 and HMS software.  The results showed that Bandsars control 100% of the runoff from rainfall up to a 10-year return period and Bandsar output relative input hydrograph has 2 sharp characteristics; 1- lag to peak and 2- peak attenuation and 76.75% of the water harvesting is infiltration and recharge groundwater recourses.

Collecting rainwater is one way to make life easier for local communities during periods of drought. The lack of uniform distribution of rainfall in all seasons makes it necessary to store the water needed by households. Iran is one of the arid and semiarid countries facing water scarcity problems, but in the city of Taleghan, average annual rainfall is above the national average. The roof surfaces were used to measure the quantity of water stored. The surface which can be created on the roofs of houses has been calculated using the SPOT 5 satellite. It has a total accuracy and a kappa coefficient of 91.2 and 88.5, respectively. While there are many benefits of the rainwater collection system, the results of this study showed that the economic benefits are different. If the estimated life of the rainwater collection system is 10 years and annual inflation increases at least 41% each year, this system is not economic. The initial capital requirement for a rainwater collection system was estimated at $ 679 ± 278. The results show that the costs of setting up a rainwater collection system and at least the 18% yearly financial interest on bank deposits are not equal. Besides the results show that the high cost of building the rainwater collection system is linked to the storage tank and it needs the government's financial support.

Water shortage is considered a serious problem in many countries in the world. Even in other countries where there is a better climatic condition thanks to a higher precipitation rate, water shortage still exists in the months and seasons with high water needs. Iran is a country located on the dry belt of the earth, and water shortage can be sensed in it. Guilan Province is different from other provinces due to its special geographical and climatic condition, and especially its high precipitation rate, which is five times higher than the whole country's average. But the time and positional distribution of precipitation is not uniform, and it severely decreases in April by the movement of precipitation systems, and this trend continues until late August. Due to the variety of climates in Guilan, the precipitation rate, temperature and also evaporation rate which is a function of temperature have a great impact on water balance. On the other hand, soil is another essential source of life. The mutual effects of climatic elements especially rain and temperature, and the moisture capacity of the soil, are some of the topics related to water balance, water shortage and soil moisture consumption. In the present study, the statistical data related to precipitation and temperature obtained from six climatic stations including Anzali, Lahijan, Astara, Qale Rudkhan and Manjil that were picked out of thirteen stations were analyzed, and the annual water shortage average was calculated. Then the distribution of water shortage among the stations was determined using the GIS software and was presented in a map. The problems in agriculture, industries, urban and rural sections caused by water shortage can be found and solved more easily using a water shortage map.

Karst groundwater is one of the primary water resources in most territories of Iran where karst topography is strongly featured. Understanding the key knowledge and research status of karst is an important prerequisite for subsequent research. This study aimed to examine the literature characteristics and research hotspots of karst based on Science direct database from 1998–2021 and scientific information database (SID) of Jihad Daneshgahi and Iranian Research Institute for Information Science and Technology (IranDoc). With systematic bibliometric analysis, insights were made into multiple aspects including research output, subject categories, journals, countries/territories, hotspots and research trends. The results showed that the general trend of global scientific publications in karst research has a negative slope with a negative growth rate of 0.91. But the trend of Iranian publications, with a positive slope and coefficient determination of 0.87 and a positive growth rate of 1.2 percent, has been increasing. The results of thematic classification of publications in the world showed that the most articles with 75.96% belong to research articles and the lowest to conference articles and editorials. Iranian articles also belong to the first order of importance to research articles with 91%, which is a larger share of the total articles than global articles. The results of analysis of the most important scientific journals related to karst showed that these journals have a very high h-index and JCR in Q1 and Q2. Keywords related to the intrinsic, structural characteristics and karst water resources systems had the highest frequency and the lowest frequency related to karst hazards.

Projection of climate change in basins is very important for determining water capacity, water resources management as well as watershed management studies and environmental hazards. Therefore, in this study, temperature and precipitation changes were projected in Atrak basin, in the northern Khorasan province. For this purpose, the output projection of canESM2 global model were used considering three scenarios of Representative Concentration Pathway (RCP) 2.6, RCP 4.5 and RCP 8.5 using SDSM as downscaling model and temperature and precipitation changes in the period (2021-2050) were compared with the base period (1995-2019). For calibration and validation of SDSM model, station observational data and NCEP/NCAR data were evaluated. MAE, MSE, RMSE and R2 correlation indices were determined to clarify the performance of the model. The results showed that the SDSM model has a high ability to simulate temperature and precipitation changes in the study area. According to the results of the CanESM2 model, in the future periods, temperature and precipitation would be increased compared to the base period, which might be from 0.9 and 1.0 degree Celsius for minimum and maximum temperatures, respectively. Most of the temperature changes would be related to the eastern parts of the study area while, the amount of precipitation in the basin would be increased from 1.5 up to 11.7 percent, the largest increase of which would be related to the central and northern regions of the basin. The highest and lowest temperature and precipitation changes in the basin are predicted based on RCP 8.5 and RCP 2.6 scenarios.