Estimation Of Effective Rainfall Research Articles

Characterization of Climate Change and Aquifer Recharge in Three Localities in the South-West of Côte d’Ivoire

Located in the southwestern part of Côte d'Ivoire, the study area's economic activity is rainfall-dependent agriculture and facing climate change impact on water resources. This study aims to improve the resilience of water users based on a better understanding of the recent manifestation of climate change. Specifically, it is to determine the episodes of rainfall variability and estimate the effective rainfall and groundwater recharge. The hydro-climatic database for this study covers more or less the period from 1977 to 2021. The characterization of rainfall variability was highlighted by the calculation of rainfall indices, while effective rainfall and recharge values were determined using the ESPERE (Estimation of Effective Rainfall and Recharge) software according to different mathematical methods. Using the non-parametric Pettitt test was possible to detect years with significant rainfall breaks. Thus, there was an alternation of deficit and surplus periods at different scales in the three localities. However, a break in the rainfall pattern occurred in 1989 in San Pedro, whereas this event took place a year later, in 1990, in the other two localities. The effective rainfall and annual recharge closely followed the rainfall evolution in the three localities at different scales. This acquired knowledge of hydrological and hydrogeological rainfall, dynamics can be used to better educate the resilience and climate change adaptation habits of the populations in the southwest region of Côte d'Ivoire.

Relationship between Measured and Computed Effective Rainfall Using Field Infiltrometers and CropWat Software under Sugarcane Land–Use System in Tropical Climate

A study was conducted to test the validity of four different mathematical models imbedded in CropWat software, which is widely used to estimate effective rainfall. The model values were statistically compared with the actual effective rainfall values measured by a field infiltrometer experiment. The study was conducted in a sugarcane land–use system under the tropical climate of Sevanagala, Sri Lanka, during the 2018 to 2019 growing season. The measured effective rainfall in the Sevanagala sugarcane growing area during the 12-month period was 1,068 mm, around 70% of the total rainfall of 1,517 mm. It was also found that 9% of the rainfall received at the top of the canopy was lost due to canopy interception. The results demonstrated the applicability of the mathematical models embedded in CropWat software to estimate the effective rainfall for sugarcane land–use systems in Sevanagala. Furthermore, the empirical regression formula embedded in CropWat software appeared to be the best-fit model for the estimation of effective rainfall because it had the highest index of agreement value, with an accuracy greater than 96%.

Performance analyses of effective rainfall estimation methods for accurate quantification of agricultural water footprint

Water footprint (WF) assessments have become a significant tool for the sustainable management in recent years. Effective rainfall (Peff) is a critical indicator for characterizing soil moisture (green water, WFgreen) and calculating irrigation requirements (blue water, WFblue). However, majority of the water footprint analyses employ empirical or numerical models to predict Peff, and the number of studies for experimental validation of these models are quite insufficient. The main scope of this study is to test the performance of commonly used Peff estimation models in relation to the soil water balance (SWB) of an experimental site. Accordingly, the daily and monthly soil water budget is estimated from a maize field which is characterized as semi-arid land with continental climate (Ankara, Turkey), equipped with moisture sensors. Then, Peff, WFgreen, and WFblue parameters are calculated using FP, US-BR, USDA-SCS, FAO/AGLW, CROPWAT, and SuET methods and compared with SWB method. Employed models were highly variable. CROPWAT and US-BR predictions were the most accurate. In majority of months, the CROPWAT method estimated the Peff with a maximum deviation of 5% from the SWB method. In addition, the CROPWAT method predicted blue WF with an error less than 1%. The widely utilized USDA-SCS approach did not produce expected results. The FAO-AGLW method provided the lowest performance for each parameter. We also find that the errors in estimating Peff in semi-arid conditions cause green and blue WF outputs to be quite less accurate than the dry and humid cases. This study provides one of the most detailed assessments about the impact of effective rainfall on the blue and green WF results with high temporal resolution. The findings of this study are important for the accuracy and performance of the formulae used in Peff estimations and to develop more precise blue and green WF analyses in the future.

A Modified LAPSUS Model to Enhance the Effective Rainfall Estimation by SCS-CN Method

In this study, LAPSUS model is modified to enhance the effective rainfall estimation by SCS curve number method. The LAPSUS model calculates discharge based on effective rainfall and routs it towards lower neighbouring grid cells following the multiple flow direction principle. Then, the sediment transport capacity and sediment transport rate are calculated in each grid cell. Finally, erosion or sedimentation is calculated by comparing the sediment transport rate with the sediment already in the transport of each grid cell. The amount of rainfall, curve number, convergence factor, discharge exponent, slope exponent, erodibility factor, and sedimentation ability factor are inputted to the application page of the modified model that was created in the C++ programming. The outputs of the model are runoff and erosion maps in ASCII format. Evaluating performance of the modified model showed a high accuracy of its results. The value of the coefficient of determination (R2) calculated 0.99 for runoff and 0.97 for erosion. The Nash-Sutcliffe efficiency was 0.96 for runoff and 0.97 for erosion. The value of the precision index calculated 0.81 for both runoff and erosion. Also, the nRMSE calculated 3% for both runoff and erosion. The result showed that the modified model capable to estimate the runoff and erosion on a landscape in a micro sub-catchment scale.

Evaluation of models and approaches for effective rainfall in irrigated agriculture - An overview

A precise estimation of effective rainfall (ER) is still needed not only for planning and management of rainfed crop production, but also for risk management strategies in farms. In this paper the most commonly used models/approaches, which are suitable for the estimation of ER for agricultural crops grown in different agro-climatic regions, are reviewed. Using different climatological data, ER have been estimated for crop growing seasons. Most commonly used empirical methods for the estimation of ER (Renfro Equation, U.S. Bureau of Reclamation Method, Potential Evapotranspiration/ Precipitation Ratio Method (India), USDA-SCS Method, Hersh field method, Indian- 1, Indian-2 method and Vietnam) are described in this paper. Apart from above mentioned methods, this paper reviewed performance evaluation of some models formulated for ER estimation. Precise estimation of ER is necessary for increasing agricultural production and design a soil-water balance model that provides more accurate calculation of .ER that directly satisfies crop water requirements. It is plays an important role for the determination of water requirements for crop as well as irrigation scheduling.

Application of spreadsheet to estimate infiltration parameters

Summary Infiltration is the process of flow of water into the ground through the soil surface. Soil water although contributes a negligible fraction of total water present on earth surface, but is of utmost importance for plant life. Estimation of infiltration rates is of paramount importance for estimation of effective rainfall, groundwater recharge, and designing of irrigation systems. Numerous infiltration models are in use for estimation of infiltration rates. The conventional graphical approach for estimation of infiltration parameters often fails to estimate the infiltration parameters precisely. The generalised reduced gradient (GRG) solver is reported to be a powerful tool for estimating parameters of nonlinear equations and it has, therefore, been implemented to estimate the infiltration parameters in the present paper. Field data of infiltration rate available in literature for sandy loam soils of Umuahia, Nigeria were used to evaluate the performance of GRG solver. A comparative study of graphical method and GRG solver shows that the performance of GRG solver is better than that of conventional graphical method for estimation of infiltration rates. Further, the performance of Kostiakov model has been found to be better than the Horton and Philip's model in most of the cases based on both the approaches of parameter estimation.

Estimation of Effective Rainfall in Wet Season Paddy

Estimation of Effective Rainfall in Wet Season Paddy

Water Balance Components in a Mature Citrus Orchard

The low water‐holding capacity of sandy soils, together with spatial and temporal variations of rainfall, require Florida citrus trees to be irrigated for optimal production. Citrus tree root systems are exposed to various hydrologic conditions because of soil temperature and water gradients due to tree canopy shading and under‐tree microirrigation. The main goal of this study was to evaluate water balance components in a mature citrus orchard grown on central Florida ridge soils with special interest in quantifying rainfall interception by a citrus canopy and its effect on effective rainfall estimation. Soil water content was monitored every 30 min at 10‐, 20‐, 40‐, and 80‐cm depths in the root zone both under and outside of citrus tree canopies. Microirrigation, rainfall, and weather data were used to calculate effective rainfall, plant water uptake, and deep drainage. We found that the tree canopy intercepted 35 and 50% of the incoming high (≥5‐mm) and low (<5‐mm) intensity rainfalls, respectively. Effective rainfall calculated without accounting for the canopy interception effect was overestimated by about 30 and 5% for the dry and wet periods, respectively. Citrus crop evapotranspiration was higher under the tree canopy (irrigated area) than outside the tree canopy (unirrigated area) during the dry season because of supplemental irrigation.

A groundwater recharge methodology for Water Framework Directive initial characterization in Scotland

Synopsis Estimation of recharge to groundwater is an important component in the characterization of groundwater bodies for the Water Framework Directive (WFD). The time scale allowed for the WFD initial characterization required a pragmatic methodology for efficient assessment of recharge to each delineated groundwater body. An assessment methodology was developed through a project funded by the Scotland and Northern Ireland Forum for Environmental Research, although it has application throughout the UK. Few recharge calculations have previously been attempted in Scotland. The environmental influences on recharge processes differ from much of the rest of the UK and the ability of the groundwater body to accept recharge is a key criteria. The method proposed is based on a water budget approach which estimates direct and indirect recharge flow components. It includes estimation of effective rainfall, actual evapotranspiration, surface run-off and interflow in addition to the potential impacts of snow-melt, bypass flows, urban recharge and surface water leakage where appropriate. This is calculated on a daily or monthly time step with the use of a spreadsheet software tool. The degree of uncertainty in the recharge estimation increases with the scarcity of data available to the groundwater body. Many recharge estimations in Scotland will rely on national-scale mapping of climatic, land use, soil and aquifer properties. It is important that the confidence in the estimation is balanced against the perceived risk of stress to the groundwater body. Validation of the recharge calculations is ongoing and the assessment of bypass flow and interflow has been determined as critical to the accuracy of the calculation.

Comparative study of effective rainfall estimation methods for lowland rice

Dastane (1974) recommended four different methods, namely evapotranspiration-rainfall ratio method, Indian-1 and Indian-2 methods and Vietnam method for estimating effective rainfall for rice crop. These methods together with the USDA-SCS method were compared against the physicallybased water balance method. The analysis was carried out using daily data of evapotranspiration (ET) and rainfall pertaining to thirteen seasons with special reference to lowland paddy rice in South India. Among the different methods, the ET-rainfall ratio and Indian-2 methods estimate the effective rainfall values nearly closer to those by the water balance method. The USDA-SCS method underpredicts values of effective rainfall compared to other methods. The ET-rainfall ratio and Indian-2 methods can be used as alternatives to the water balance method for determining effective rainfall which in turn be used in estimating irrigation requirements for lowland rice.

An Estimation of Effective Rainfall on a Small Mountain Watershed

An Estimation of Effective Rainfall on a Small Mountain Watershed