Rainfall characteristics, which include spatial Variability, exert a major influence on runoff properties. Many techniques have been proposed for determining the spatial distribution of daily Rainfall. One of these techniques is spatial modeling, based on Rainfall data measured by rain-gauge networks. In this study, application of different interpolation methods in the GIS environment, for estimating the spatial distribution of daily Rainfall in the southwest of Iran with low rain-gauge density, have been compared on a regional scale. The cross validation technique was selected as an accuracy index and statistical parameters, such as MAE (Mean Absolute Error) and MBE (Mean Bias Error), were used for comparing the results of cross validation. The ranking of MAE and MBE values was used for determining the best interpolation method. The interpolation methods that were studied for mappingthe spatial distribution of daily Rainfall include nearest point, moving average, moving surface, trend surface and kriging. Since the spatial pattern of daily Rainfall is random, the moving average method, with inverse distance weight function, was determined as the best method for interpolating daily Rainfall data in the region of study.

Introduction The consequences of climate change, changes in precipitation characters, including the amount, time and it’ s duration are expected. Considering that the rain provides the water resources on the planet, change in regime, amount and duration of Rainfall, caused a disturbance in the ecosystem of the Earth. It also affects the environmental conditions. Kurdistan province has an agricultural economy, thus variation in the Rainfall duration can affect agricultural activity and other activities. To achieve success in the environmental management planning and efficient use of water resources over an area, it is essential to have information about Rainfall variation. An important parameter of atmospher is precipitation. It has a lot of changes over the time and space. It is a basic element in the formation of the activities and prospects of the environment. Several studies have done by researchers on the properties of precipitation in the different regions of the world and also in Iran. In general, precipitation showed a negative trend in many regions (Gorgio, 2002: 675). For example, an assessment of summer Rainfall in eastern China showed a positive and a negative trend in the north (Gemmer et al, 2004: 39; Gong et al, 2004: 771). Annual Rainfall has decreased in southern parts of Italy and the decrease in winter precipitation was larger (Marco et al, 2004: 907). An increase in summer Rainfall, especially, in June and July has been reported in the Yangtze River basin (Tong et al, 2007: 1016). A decrease in winter Rainfall and an increas for other seasons has been showed in Turkey (Kahya and Partal, 2007: 43). Evaluation of maximum daily Rainfall at the global scale showed an increasing trend in Rainfall (Sethwestra et al. 2013: 3904). Negative anomalies of precipitation was reported for the most stations in southern west Ethiopia (Girma et al. 2016: 3037). Based on Iran's annual Rainfall, positive and negative trends in annual Rainfall have been showed (Asgari and Rahimzadeh, 2006: 67). A decrease in Rainfall, especially in the decade of 1995-2005 revealed in Iran using annual Rainfall (Asakereh and Razmi, 2012: 159). Assessment of changes in seasonal patterns of Rainfall in Hamedan, showed that the beginning of the rain tend to the summer and the end of winter (Movahedi et al., 2013: 23). The results of precipitation extreme indices on Iran showed a positive trend in the west and the south west and a negative trend in the north (Masoodian and Darand, 2013: 239). Methodology For this study, the daily precipitation obseravtions obtained from synoptic stations in Kurdistan province during 01. 01. 1989 to 31. 12. 2014 were anlayzed. A database with dimensions of 9526 * 8 was created. The time was set on rows (9526 days) and the Rainfall was set on columns. Homogeneous and heterogeneous monthly Rainfall data were assessed by apply cumulative deviations test and Vercelli maximum of likness. Mann-Kendall approach was implemented to extraxt the trend at the significant level of 90%, 95%, and 99 %. The significant differences in the mean of time series data before and after a mutation year by Mann-Whitney test were evaluated. The statistical calculations were done in the Matlab software. Results and Discussion The results showed that during the study period, duration of Rainfall for autumn, winter and spring, in most of the stations, has been reduced. The results indicated that the Rainfall duration for summer showes an increases in Rainfall. Which is in line with the result of many previous studies. The reduction in the Rainfall in the rainy season and an increase in Rainfall in summer were obsorved. As a result the duration Rainfall also has been changed. Annual Rainfall has decreased in southern Italy and decrease in precipitation in winter is more (Marco et al, 2004: 907). Movahedi et al. 2013, By studying the seasonal Rainfall in Hamadan, They found that the Rainfall began to ward the winter and their end to the summer have changed. Conclusion Evaluation of duration time series of Rainfall over different months of the year showed that in the rainy months of autumn, winter and spring Rainfall duration has decreased. For example, Baneh station showed a decline of 0. 3 day in December, and Marivan showed a decline of 0. 6 day in January. The average rate of decline in Rainfall duration in March for the Qorveh station was 0. 4 day per decade. In addition, a decline in spring Rainfall duration was observed as well. Bijar station showed a decline of 0. 2 day in May. However the Rainfall duration in summer showed an increase. For example, Zarinah station obtained an increase of 0. 2 day per decade in August.

Introduction One of the important consequences of climate change is a change in the frequency and intensity of Rainfall. In fact, it can be said that as a result of this phenomenon (climate change), in many parts of the world, the frequency and intensity of maximum Rainfall have increased. However, the type and severity of these changes vary from region to region (IPCC, 2012: 5). In recent decades, in the framework of climate change, several studies have been conducted on the trend of Rainfall in most parts of the world. Most of these studies are based on parametric or non-parametric methods such as linear regression analysis, Spearman's test, age gradient test, and Mann-Kendall test. However, the use of these methods requires some limiting assumptions. In addition, these tests only show the trend of changes in the average time series, while they do not provide any information about the trend of changes in different time series classes. In this regard, Sen (2012: 1044) proposed the ITA method, which addresses the above-mentioned problems in addition to allowing a trend to be identified in a series of "low", "medium" and "high" values. Materials and methods In this study, in order to achieve the defined goal, the basic method of percentiles was initially used. Since the choice of the threshold value of the base percentile is a matter of taste and does not reflect the intensity-frequency of heavy Rainfall, the type 1 equation probabilistic distribution function (Gamble) was used to determine the heavy precipitation threshold to provide a criterion that results in intensity-frequency of occurrence, while it is based on time series distribution of the precipitation data. For this purpose, first the data of rainy days related to 6 synoptic stations in the west of the country from 1961-2019 were obtained from the Meteorological Organization. Then, in order to calculate the maximum amount of daily Rainfall during different return periods, the Gamble distribution function was used, based on which the heavy Rainfall threshold was defined for the stations in the region and the maximum daily Rainfall values during the return periods of 2, 5, 10, 15, 20, 25, 50 and 100 years were calculated. Finally, MK and ITA tests were used to determine the trend of these precipitations. The ITA method was proposed by Sen. Despite its simplicity, it does not require any presuppositions and is more capable than other non-parametric methods because this method is able to identify hidden trends and internal trends in time series in addition to uniform trends. Therefore, in this study, ITA method was used to identify the uniform and non-uniform trends in the maximum daily Rainfall and the total annual Rainfall in the west of the country. Research Findings After determining the thresholds of heavy Rainfall using the Gamble distribution function, it became clear that the average Rainfall of more than 37 mm in the western region of the country is considered heavy Rainfall. The heavy Rainfall index of Dezful station was higher than other stations, which indicates the high intensity of daily Rainfall in this station. In this study, heavy precipitation threshold was calculated for all stations by applying the percentile method on rainy days with a minimum threshold of 1 mm. Then, ITA method was used to analyze the trend and determine the behavior of total annual Rainfall and maximum daily Rainfall in the study area. Application of this method on the total annual Rainfall of Khorramabad station showed that middle floor precipitation (430-650) of this station is decreasing, while upper and lower floor precipitation was decreasing. In Hamedan station, the precipitation of the middle class (240-240) showed a significant decreasing trend, but no significant trend was observed in the lower class (less than 240) and the upper class (above 440). In Kermanshah, Dezful, Ahvaz and Abadan stations, the trend specified in all classes was decreasing and uniform. The application of Man-Kendall method on the total annual Rainfall in the study area showed that the trend of these rains is decreasing in all stations and is significant in Khorramabad, Hamedan, Kermanshah and Dezful at the level of 95%. Regarding the application of ITA method for maximum daily Rainfall of Gamble, the results showed that in Khorramabad station, Rainfall with a return period of 5, 10, 15, 20 and 25 years of this station increased and precipitation with a return period of 2 years showed no particular trends. At Abadan station, Rainfall with a return period of 50 years showed a decreasing trend. In Dezful and Ahvaz stations, the trend marked in all classes was a decreasing trend. In general, no specific trend was observed in Hamedan and Kermanshah stations. Regarding the maximum daily Rainfall of Gamble, the results of Mk showed a negative trend in Hamedan, Kermanshah, Ahvaz and Abadan stations and a positive trend in Khorramabad and Hamedan, but only in Ahvaz station, the trend was significant at 95%. In the present study, some conflicting results have been obtained by comparing the ITA and MK methods. This shows the advantage of this method over other process tests. For example, while the Mann-Kendall test on Khorramabad station showed a significant decrease in the total annual Rainfall of this station, the Sen method showed a different trend from this method. In fact, according to ITA, it was found that the total Rainfall in Khorramabad had an uneven trend, which was divided into three classes, and the precipitation class showed 430 to 650 decreasing trends less than 430 and more than 650 increasing trends in this station. Result The results of ITA method showed that on an annual scale, there is a non-uniform trend in Rainfall in Khorramabad and Hamedan. But in Kermanshah, Dezful, Ahvaz and Abadan stations, the trend marked in all classes was decreasing and uniform. On a daily scale, the results showed that precipitation with a return period of 5, 10, 15, 20 and 25 years of this station is an increasing trend and precipitation with a return period of 2 years is without a trend. At Abadan station, Rainfall with a return period of 50 years showed a decreasing trend. In Dezful and Ahvaz stations, the trend marked in all classes was a decreasing trend. In Hamedan and Kermanshah stations, in general, no specific trend was observed, but in more detail, it can be said that the trend of Rainfall on the upper floor of Hamedan station was increasing, whereas the trend was decreasing in Kermanshah station. The results of Mann-Kendall test also showed that on an annual scale, all stations have a decreasing trend and on a daily scale, Hamedan, Kermanshah, Ahvaz and Abadan stations have a negative trend, although Khorramabad and Hamedan stations showed a positive trend in precipitation. In fact, when there is a non-uniform trend in the time series, the MK test shows that the trend is insignificant, but the ITA method detects such non-uniform trends and makes hidden time series information available.

BACKGROUND AND OBJECTIVES: Understanding spatial and temporal Rainfall Variability is essential for effective water resource management in Indonesia, where diverse landscapes and dynamic tropical climates cause uneven precipitation that often leads to localized floods or droughts. This study aims to investigate how geomorphological and topographical differences across the Toba-Asahan, Brantas, and Larona-Malili watersheds in Indonesia influence Rainfall distribution and trends, in order to support adaptive and sustainable watershed management.METHODS: This study analyzes Rainfall Variability in three distinct Indonesian watersheds, Toba-Asahan, Brantas, and Larona-Malili, using climate hazards group infrared precipitation with Station version 2 satellite precipitation data. The spatial and temporal patterns of Rainfall are examined in relation to each watershed’s unique geomorphological and topographical characteristics. Basic statistical analysis and mapping techniques are used to identify trends and visualize distribution patterns, aiming to provide insights into how natural landscape features influence Rainfall behavior and water availability at the watershed scale.FINDINGS: The results reveal a significant long-term increase in Rainfall in the Larona-Malili watershed, while no statistically significant trends are observed in the Brantas and Toba-Asahan watersheds. The dominant Rainfall patterns reflect the unique regional climatic characteristics of each watershed. Spectral analysis highlights the influence of El Niño Southern Oscillation and Indian Ocean Dipole, showing semi-annual Rainfall patterns in Toba-Asahan and Larona-Malili, and an annual cycle in Brantas. Climatic sensitivity differs across the three watersheds, as reflected by the varying influence of the Webster-Yang Monsoon Index, El Niño Southern Oscillation, and Indian Ocean Dipole.CONCLUSION: This study comprehensively analyzes Rainfall Variability in three significant watersheds in Indonesia; the Brantas, the Toba-Asahan, and the Larona-Malili watersheds. Another finding from this study is that seasonal Rainfall patterns in the Brantas watershed is significantly influenced by the Asian Monsoon. In contrast, the Toba-Asahan and Larona-Malili watersheds are shaped by local and regional factors, with land use changes playing a role in Rainfall Variability and water resource impacts. Annual patterns vary among the watershed, with Toba-Asahan experiencing year-round Rainfall peaking from August to December, Brantas dominated by afternoon convection-driven rain from January to April and November to December, and Larona-Malili showing morning-to-noon Rainfall from May to July due to local circulation and topographic effects. The findings provide valuable insights into managing water resources and addressing climate change and extreme weather Variability in Indonesia. In conclusion, the overall results of this study may serve as a basis for water resource management in the three watersheds, especially in the face of potential climate change and extreme weather Variability.

Rainfall erosivity is the ability of Rainfall to detach the soil particles. This study was conducted to evaluate spatial Variability of Rainfall erosivity indices in Khouzestan Province. The point data of indices (EI30, AIm, KE>1 and Onchev indices) in 74 stations were used to generate spatial erosivity maps through deterministic and geostatistical interpolation methods (Radial Basis Functions, Inverse Distance Weighted, Kriging and Cokriging). Results indicate that cokriging have least error and most correlation with determining coefficient of 0.89, 0.89, 0.48 and 0.49 for EI30, AIm, KE>1 and Onchev indices. Based on the correlation relationships between the basins specific sediment yield (in basins dominating the sedimentation stations) and mean indices of EI30, AIm, KE>1 and Onchev, EI30 index with correlation coefficient of 0.98 (P<0.01) is selected as the appropriate Rainfall erosivity index. Based on the prepared map on the basis of Cokriging method with secondary variable of maximum mean monthly Rainfall, the east and northeastern regions presented the highest values of EI30 index, while the southern and western regions showed the lowest values of EI30 index. The annual Rainfall erosivity (EI30) ranged from 404 to 3064 Mj.mm.ha-1.h-1.y-1.

Rainfall erosivity factor is the most important factor influencing soil erosion. Various indicators has been developed to quantify it. Selection the appropriate index due to ecological conditions is necessary. Therefore mapping Rainfall erosivity and awareness its changes, plays an important role in soil conservation, erosion control and land management. The purpose of this study is the selection of the best geostatistic method for mapping the Rainfall erosivity factor in Fars province. In first step Fournier factor was calculated for 42 stations in Fars province and its surrounding and was determined the best geostatistic method using IDW, GPI, LPI, RBF, Ordinary and Simple and was prepared zoning map for Fournier factor. The results showed that among the various geostatistic techniques, RBF method (Thine plate Spline) is the best method for mapping Rainfall erosivity factor in Fars province. Also, Noorabad city in northwest of province with an average of 31. 6 mm Fournier and Izadkhast city with 8. 67 were determined as the highest and lowest of the erosivity index. Also, Fournier index has increased from the East to the West as 46% of the province has a low erosion and 3% of the province has been high erosion that have had the highest and lowest levels.

In this study, we address a broad question that relates foreign development aid to economic growth in 41 Sub‐ Saharan African (SSA) countries employing panel data spanning a twenty‐ five‐ year period. The panel data was analysed using fixed effect Ordinary Least Square (OLS) model. We explored the within‐ country Rainfall distribution to identify the impact of foreign development aid per capita (Value of Official Development Assistance) on GDP per capita. Identifying aid with exogenous Rainfall shocks will plausibly address the endogeneity bias identified in previous studies. In the first stage, we find that Rainfall shocks negatively correlate with amount of aid per capita received suggesting that countries with negative economic shock receive more foreign assistance than countries without. However, in stage two, we find that aid per capita has a statistically weak and negative impact on income per capita in the region. We can identify several practical reasons why aid may fail to translate to growth in this region. For one, because aid is a form of unearned rents, aid meant for public consumption could be privately appropriated by political elites, distort capital accumulation, and could undermine the broader economic development when there is an income shock. While SSA countries receiving aid may not grow faster than countries without, aid might still play an economically useful role at the micro‐ level. Specifically, aid could be beneficial if local inputs at the micro‐ level are actively involved in allocation of resources and deployed for the identification of developmental needs. Aid could also be useful at suppressing civil conflict associated with climate vagaries.

Rainfall and flow rate are of the most important climatic and hydrologic parameters whose investigation and determination of their behavior are of great importance in water resources management. One of the most suitable methods available for assessment of hydroclimatological conditions in the watershed is trend analysis which is used to examine the changes of a variable during time. Current study has been implemented in two parts. The first part of the study investigates the effect of Rainfall changes on Darakeh river flow rate between 1989-2012. To do this, monthly recorded data of Rainfall from Haft Howz station (on Darakeh River) and methods such as graphical Mann-Kendall and linear regression tests were used. In addition, Rainfall and river discharge anomalies were examined during the 24-year period. The results indicate that Rainfall time series in Darakeh watershed has a positive and rising trend, though this trend is not significant. Also river flow rate increases with a slight slope during the studied time period and doesn’ t show a significant trend. Totally it can be concluded that except for some particular time periods, increase and decrease in the amount of Rainfall and river flow rate has not been concordant. The second part predicts the future Rainfall in the catchment using MRI-CGCM2. 3. 2a under A1B emission scenario for three time horizons (2030, 2060, and 2090). The overall results are representative of reduction in Rainfall in Darake river basin in the future.