Net Irrigation Water Research Articles

Modelling the irrigation demand profile of Chalakudy river diversion scheme using CROPWAT and GIS tools

Irrigation planning for a command area necessitates a proper assessment of irrigation water required by the crops in the area. Net irrigation water demand mainly depends on the cropping pattern and the areal extent. In a vast command area collection of accurate data on cropping pattern and their areal extent is a tedious job. Remote sensing technology and geographic information systems could be utilized effectively for easy and accurate data collection. Rainfall is another important factor in the calculation of irrigation water requirement. Effective rainfall retained in the root zone of crops reduces irrigation requirement. In the present study the average rainfall of the entire command area was calculated using the Thiessen polygon method. The land use map of CRDS command area was prepared using remote sensing and GIS tools. From the prepared land use map, areal coverage of crops in the command area was assessed for the computation of irrigation water requirement. Cultivated crops covered more than 80 per cent of the CRDS command area that comprised paddy 10.51 per cent, mixed crops 37.77 per cent, coconut-dominant mixed crop 31.83 per cent and rubber 12.80 per cent. CROPWAT 8.0 software was used for the computation of irrigation water requirement. The average annual net irrigation demand of CRDS command area was obtained as 46.90 Mm3.

Remote sensing-based soil water balance for irrigation water accounting at the Spanish Iberian Peninsula

Abstract. Temporal series maps of irrigated areas, and the corresponding irrigation water requirements based on remote sensing, is a recognized tool contributing to water governance at different scales, from water user associations to whole river basin districts. These thematic cartographies offer a first estimation of the crop irrigation requirements, and a biophysical based approach of the temporal and spatial distribution of the crop water use in the cultivated areas. This work describes the operational application of these methodologies, providing valuable information for water governance and management purposes. The basic products obtained in the whole Spanish part of the Iberian Peninsula during the period 2014–2017 were: (i) annual maps of irrigated crops based on time series of multispectral satellite imagery; and (ii) the direct remote sensing-based water accounting, by quantifying agricultural water flows (e.g. rainfall, irrigation, evapotranspiration, drainage and recharge), through a remote sensing-based soil water balance. Hence this paper provides a remote sensing based water accounting approach, which relies on dense time series of multispectral imagery acquired by the multisensor constellation arranged by Landsat 8 and Sentinel-2 satellites, jointly with meteorological data and agronomic knowledge. Then, based on these purpose and approach, annual and monthly maps of net irrigation water requirements have been elaborated at the most practical spatial and temporal scales for water governance purposes over big areas such river basin districts. This work summarizes the methodologies used and discuss the technical and non-technical feasibility of the proposed approach.

Study of the water saving potential of an irrigation area based on a remote sensing evapotranspiration model

To estimate the water saving potential of an irrigation area and create a scientific water saving plan, the irrigation water use efficiency and water productivity of the Hulanhe irrigation area for 2007–2014 were calculated, and the water saving potentials of different water saving plans were determined from the perspectives of engineering and crop water saving. The results showed that the evapotranspiration calculated from the surface energy balance algorithm for land model (SEBAL) agreed well with the measured results. The irrigation water use efficiency in the Hulanhe irrigation area was positively correlated with precipitation of irrigated land and was negatively correlated with the net irrigation water volume. The engineering water saving potential ranges for periods of 5, 8, 11, and 15 years were (1.702 × 108, 5.103 × 108) m3, (1.783 × 108, 5.184 × 108) m3, (1.865 × 108, 5.266 × 108) m3, and (2.301 × 108, 5.702 × 108) m3, respectively, and the water saving potential increased year over year. Low amounts of precipitation of irrigated land corresponded with small amounts of net irrigation water and greater water saving potential. Based on the cumulative frequency of the water productivity calculated for the Hulanhe irrigation area from 2007 to 2014, the target water productivity for short (50% of the multi-year average cumulative water productivity) and long (70% of the multi-year average cumulative water productivity) terms were 1.03 kg/m3 and 1.22 kg/m3, respectively, and the cumulative crop water saving potentials for short and long terms were 1.18 × 108 and 2.74 × 108 m3, respectively. These results provided a theoretical reference for creating water saving plans for irrigation areas.

Irrigation Performance Assessment in Table Grape Using the Reflectance-Based Crop Coefficient

In this paper, we present the results of our study on the operational application of the reflectance-based crop coefficient for assessing table grape irrigation requirements. The methodology was applied to provide irrigation advice and to assess the irrigation performance. The net irrigation water requirements (NIWR) simulated using the reflectance-based basal crop coefficient were provided to the farmer during the growing season and compared with the actual irrigation volumes applied. Two treatments were implemented in the field, increasing and reducing the irrigation doses by 25%, respectively, compared to the regular management. The experiment was carried out in a commercial orchard during three consecutive growing seasons in Northern Chile. The NIWR based on the model was approximately 900 mm per season for the orchard at tree maturity. The experimental results demonstrate that the regular irrigation applied covered only 76% of the NIWR for the whole season, and the analysis of monthly and weekly accumulated values indicates several periods of water shortage. The regular management system tended to underestimate the water requirements from October to January and overestimate the water requirements after harvest from February to April. The level of the deficit of water was quantified using such plant physiological parameters as stem water potential, vegetative development (coverage), and fruit productivity. The estimated NIWR was roughly covered in the treatment where the irrigation dose was increased, and the analyses of the crop production and fruit quality point to the relative advantage of this treatment. Finally, we conclude that the proposed approach allows the analysis of irrigation performance on the scale of commercial fields. These analytic capabilities are based on the well-demonstrated relationship of the crop evapotranspiration with the information provided by satellite images, and provide valuable information for irrigation management by identifying periods of water shortage and over-irrigation.

Grain yield, biomass productivity and water use efficiency in quinoa (Chenopodium quinoa Willd.) under drought stress

Five quinoa cultivars introduced from Egypte DRC (Desert Research Center-Caire) were tested in an experimental station in Tunisia located under arid climatic conditions. In order to test their adaptation to abiotic constraints; water requirements, yield (grain, dry matter) and water use efficiency (WUE) were correlated to three water stress: T100% of field capacity (T1), T60% of field capacity (T2) and T30% of field capacity (T3). Net irrigation water requirement was estimated using CROPWAT 8.0 software. The study aims to develop an irrigation scheduling for quinoa from January to Jun during 2015 season. The ET0 was between 1.08 mm/day and 4.95 mm/day and net irrigation water requirement was 287.2 mm. For grain yield, 1000 grains weight and dry matter production results show significant differences between cultivars and water stress. The seeds productivity of the five cultivars ranges between 2092.6kg/ha and 270kg/ha under full irrigation and it decreases to reach up 74% under T3 of field capacity stress in comparison with control stress. Similar results were shown for dry matter production. On refilling soil to field capacity with irrigation at critical depletion, 70% field efficiency was achieved which correspond to optimal condition, while adapting fixed interval per stage. For WUE, highest value of irrigation and total water use efficiency for both grain and dry matter ​​were recorded to the T2 hydrous stress.

Reference evapotranspiration (ETo) and irrigation water requirement of different crops in Bihar

For irrigation scheduling and better management of the water, estimation of irrigation water requirement of the crop is essentially required. The study was conducted for estimation of daily reference evapotranspiration (ETo) by FAO Penman-Monteith method using 30 years (1985-2015) mean meteorological data of two locations Sabour (zone III A) and Patna (zone III B) in Bihar. The crop evapotranspiration was estimated using crop coefficients of different crops like rice,kharif maize, wheat, rabi maize, green gram and summer maize at Sabour and Patna locations. Irrigation water requirement for different crops was estimated based on crop evapotranspiration and effective rainfall during the growing period of the crop. The mean annual reference evapotranspiration (ETo) was found 3.6 mmday-1 at Sabour and 4.1 mmday-1 at Patna. The total crop evapotranspiration was maximum for rice crop in kharif season 546.0 and 607.3 mm at Sabour and Patna respectively and lowest for wheat crop in rabi season 212.9 mm and 243.3 mm at Sabour and Patna respectively. Net irrigation water requirement was maximum for summer maize366.3at Sabour and 508.2 mm at Patna for rice crop whereas lowest in kharif maize 67.5 and 161.4 mm at Sabour and Patna respectively.

GCM‐related uncertainty in forecasting irrigation and design water requirement for paddy rice fields

ABSTRACTThe aim of this study is to identify the global circulation model (GCM)‐related uncertainties regarding the climate‐change impacts that affect the water management in paddy rice fields. The crop evapotranspiration, effective rainfall, net irrigation water requirement (NIWR), and design water requirement (DWR) were simulated from 1981 to 2100 using 36 climate‐change outputs of 23 GCMs. In particular, the DWR indicates the NIWR of a drought with a 10‐year return period, which is used for the design of an agricultural reservoir in the Republic of Korea. The NIWR is the main factor for determining irrigation water supply and managing agricultural water resource. The average changes of the NIWR compared with the periods from 1981 to 2014 are from 5.2 to 8.3% in the central region and from 3.2 to 6.1% in the southern region under RCP (representative concentration pathways) 4.5. The largest increase from the average NIWR was simulated by the MIROC‐ESM (745.8 mm year−1). These results showed that the selection of GCM could lead to overestimates or underestimates of the potential impacts of climate change. Therefore, water managers should consider that each GCM simulated a different NIWR to enable the application of the appropriate GCMs for drought management, water‐resource development, or irrigation supply. Under the GCMS variations, an NIWR was identified, thereby allowing for a DWR estimation for which multi‐GCMs were used. Under RCP 4.5, the DWR gradually increased in future periods compared with the trends from 1981 to 2014, and the average rates increased 9.4% and 6.0% in the central and southern regions, respectively. The results showed that if the capacity of an agricultural water‐resource facility is maintained at its present status, an increase of the DWR may lead to water‐supply shortage.

Responses of field evapotranspiration to the changes of cropping pattern and groundwater depth in large irrigation district of Yellow River basin

To solve the problems of decreasing water resources from the Yellow River, the renovation project of water-saving and controlling water distribution was implemented in the Hetao Irrigation District of North China since 1999. The local hydrological cycle is expected to be influenced or changed during the past fifteen years through the project. Jiefangzha Irrigation Region, the second large partition of the Hetao Irrigation District, was selected as the typical area to explore the relationship between agricultural water consumption, water distribution, cropping pattern and changing groundwater level. In this paper, the SEBS (Surface Energy Balance System) model and the ESTARFM (Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model) algorithm were applied to produce daily field-scale evapotranspiration (ET) based on Landsat and MODIS data from 2000 to 2015 at intervals. The results indicate that the cropping pattern had changed greatly, while the water table descended through the years. The total agriculture ET stayed relatively stable, with the average annual consumption of 8.9×108m3. The temporal variation of agriculture ET was not obviously sensitive to the adjustment of cropping pattern. There was no significant difference in April–October ET for different crops, in spite of the clear distinction of ET in each crop-specific growing season. The spatial distribution of agricultural ET did not change in spite of the great adjustment of cropping pattern during fifteen years, which has a close inverse correlation with the groundwater depth. Groundwater depth descended from 1.76m to 2.33m during the operation period of the water-saving project, which might reduce the soil evaporation and have a positive effect on soil salinization effectively. Meanwhile, the net irrigation water use efficiency was improved from 0.59 to 0.66. These effects indicate the positive impact of the implemented water-saving renovation project on water management and environment. However, the actual crop coefficient Kc,a decreased slightly with the gradually increasing reference evapotranspiration, indicating possible drought stress as an effect of the continuing reduction of the availability of net irrigation water and declining groundwater table.

RESPONCE A CONSUMPTIVE USE PROGRAM MODEL ON WHEAT UNDER EGYPTIAN CONDITIONS

The experiments were carried out at Moshtohor, Kalubia governorate [Latitude: 30o 21`N, Longitude: 31o 14`E and Elevation: 14 m] during 2015/16 growing seasons to test model application of wheat under Egyptian conditions. A computer application program has been developed as Consumptive Use Program plus (CUP plus) as is an application, can estimate crop evapotranspiration (ETc) and evapotranspiration of applied water (ETaw). A monthly climate data, the program uses daily measured weather data to estimate daily soil water balances for surfaces that account for evapotranspiration losses and water contributions from rainfall, seepage, and irrigation. Soil water-holding characteristics, effective rooting depths, and irrigation frequency were measured with rainfall and ETc data to calculate a daily water balance and determine effective rainfall and ETaw, which is equal to the seasonal cumulative ETc minus the effective rainfall. The main objective of this paper research is testing a mode for determining reference evapotranspiration (ETo), crop coefficient (Kc) values, crop evapotranspiration (ETc), and evapotranspiration of applied water (ETaw), which provides an estimate of the net irrigation water diversion needed to produce a crop. The obtained results show that ETo arrive to the maximum in May by 188.19 mm/month but ETaw arrive to the maximum in April by 110.71 mm/month. The application outputs a wide range of tables and charts that are useful for irrigation planning and decision making.

Changes in irrigated land and agricultural water use in the Lake Urmia basin

ABSTRACTHesami A, Amini A. 2016. Changes in irrigated land and agricultural water use in the Lake Urmia basin. Lake Reserv Manage. 32:288–296.In the Urmia basin, intensive agriculture relies heavily on irrigation systems using river-fed irrigation canals and groundwater-supplied pressure systems, causing Lake Urmia to shrink in recent years. The loss of lake area has diminished the productivity of surrounding agricultural lands and caused environmental out-migration and substantial economic losses. Because water resources in the Lake Urmia basin are limited, the government has prohibited new development plans and determination of new water rights. In this study, remote sensing, geographic information systems, and data gathered from official organizations were used to quantify the change in area under irrigation and water consumption. Multi-date Landsat Thematic Mapper imagery was employed to derive the land use map. The study was conducted in the Miandoab alluvial plain, a 1025 km2 area in the southeast part of the Lake Urmia basin, located in northwest Iran. Crop data gathered from field observations were used to verify the land cover map. To quantify the change in agricultural water use, the net irrigation water requirements for each crop were determined using the CROPWAT model, and the reference evapotranspiration was estimated using the Penman–Monteith equation. The results of this study indicated a 19,363 ha increase in total irrigated area (≈20%) and a 226 million cubic meter increase in water demand (≈35%) for irrigation during the study period. This research highlighted the role of integrated water resources management as a framework to develop the agricultural lands in the basins.

Irrigation water requirements of different crops in Limbasi branch canal command area of Gujarat

In this paper, the net irrigation water requirement estimation is carried out for different crops in Limbasi branch canal command area of Mahi Right Bank Canal (MRBC) project located in Gujarat, India. The Hargreaves – Samani approach for reference crop evapotranspiration (ETo) estimation is used for thirteen years of available data and the mean monthly ETo values were computed which were analyzed statistically. The potential crop evapotranspiration (ETc) and net irrigation requirement (NIR) of different crops in kharif, rabi and summer season were estimated. Results show that the NIR values (mm) for kharif crop paddy was 166.8; rabi crops jowar, tobacco & wheat were 404.3, 504.2 & 564.7 and summer crops paddy & bajri were 851.1 & 619mm respectively.

Optimal Irrigation Scheduling for Summer Maize Crop: Based on GIS and Cropwat Application in Hetao District; Inner Mongolia Autonomous Region, China

Net Irrigation Water Requirement was estimated using GIS and CROPWAT software. The study aims to develop an optimal irrigation scheduling in summer, to increase crop yield under water scarcity conditions. The proportion of rainwater evaporated over year 2008 “868.6 mm/dec” was used to compare with the water requirements of the maize crop “734.1 mm/dec” The results showed deficits ranging between 30.7 mm/month and 200.8 mm/month, for the period between April and September. In addition, there was uneven distribution of precipitation and an irregular basis during the agricultural year (2000-2008). The ET 0 was between 0.47mm and 3.08mm, and net irrigation water requirement was 833.4 mm for the maize crop. On refilling soil to field capacity with irrigation at critical depletion, 70% field efficiency was achieved which correspond to optimal condition, while adapting fixed interval per stage gave a yield reduction of about 2.5 %. Keywords: Evapotranspiration; ArcGIS; CROPWAT; Optimal Irrigation Scheduling; Corn

An assessment of global net irrigation water requirements from various water supply sources to sustain irrigation: rivers and reservoirs (1960–2050)

Abstract. Water supply sources for irrigation (e.g. rivers and reservoirs) are critically important for agricultural productivity. The current rapid increase in irrigation water use is considered unsustainable and threatens food production. In this study, we estimated the time-varying dependence of irrigation water requirements from water supply sources, with a particular focus on variations in irrigation area during past (1960–2001) and future (2002–2050) periods using the global water resources model, H08. The H08 model can simulate water requirements on a daily basis at a resolution of 1.0° × 1.0° latitude and longitude. The sources of irrigation water requirements in the past simulations were specified using four categories: rivers (RIV), large reservoirs (LR) with a storage capacity greater than 1.0 × 109 m3, medium-size reservoirs (MSR) with storage capacities ranging from 1.0 × 109 m3 to 3.0 × 106 m3, and non-local non-renewable blue water (NNBW). The simulated results from 1960 to 2001 showed that RIV, MSR and NNBW increased significantly from the 1960s to the early 1990s globally, but LR increased at a relatively low rate. After the early 1990s, the increase in RIV declined as it approached a critical limit, due to the continued expansion of irrigation area. MSR and NNBW increased significantly, during the same time period, following the expansion of the irrigation area and the increased storage capacity of the medium-size reservoirs. We also estimated future irrigation water requirements from the above four water supply sources and an additional water supply source (ADD) in three future simulation designs; irrigation area change, climate change, and changes in both irrigation area and climate. ADD was defined as a future increase in NNBW. After the 2020s, MSR was predicted to approach the critical limit, and ADD would account for 11–23% of the total requirements in the 2040s.

Impacts of climate change on winter wheat water requirement in Haihe River Basin

Climate change and variability has the potential to impact crop growth by altering components of a region’s water balance. Evapotranspiration driven by higher temperatures can directly increase the demand of irrigation water, while indirectly decreasing the length of the annual crop growth period. The accompanying change in precipitation also affects the need to supply irrigation water. This study focuses on the spatial and temporal variation of historical and future irrigation water requirements of winter wheat (Triticum aestivum L.) in the Haihe River Basin, China. Irrigation water requirement is estimated using a simple water balance model. Climate change is incorporated by using predicted changes in daily precipitation and temperature. Changes in evapotranspiration and crop phenophase are then calculated for historical and future climate. Over the past 50 years, a decrease in total net irrigation water requirement (NIR) was observed mainly due to a reduction in the crop growth period length. The NIR is shown to decrease 2.8∼6.9 mm with a 1-day reduction in growth period length. In the future, sowing period will come later and the heading period earlier in the year. The NIR in November, March and April is predicted to increase, especially in April. Increased NIR can result in increased water deficit, causing negative impacts on crop yield due to water stress. In the future, more attention should be paid to water resource management during the annual crop growth period of winter wheat in the Haihe River Basin.

Impact of climate change on regional irrigation water demand in Baojixia irrigation district of China

Water scarcity in China would possibly be aggravated by rapid increase in water demand for irrigation due to climate change. This paper focuses on the mechanism of climate change impact on regional irrigation water demand by considering the dynamic feedback relationships among climate change, irrigation water demand and adaptation measures. The model in implemented using system dynamics approach and employed in Baojixia irrigation district located in Shaanxi Province of China to analyses the changes in irrigation water demand under different climate change scenarios. Obtained results revealed that temperature will be the dominant factor to determine irrigation water demand in the area. An increase of temperature by 1 °C will result in net irrigation water demand to increase by about 12,050 × 104 m3 and gross water demand by about 20,080 × 104 m3 in the area. However, irrigation water demand will not increase at the same rate of temperature rise as the adaptation measures will eventually reduce the water demand increased by temperature rise. It is expected that the modeling approach presented in this study can be used in adopting policy responses to reduce climate change impacts on water resources.

Monitoring of Irrigation Schemes by Remote Sensing: Phenology versus Retrieval of Biophysical Variables

The appraisal of crop water requirements (CWR) is crucial for the management of water resources, especially in arid and semi-arid regions where irrigation represents the largest consumer of water, such as the Doukkala area, western Morocco. Simple and (semi) empirical approaches have been applied to estimate CWR: the first one is called Kc-NDVI method, based on the correlation between the Normalized Difference Vegetation Index (NDVI) and the crop coefficient (Kc); the second one is the analytical approach based on the direct application of the Penman-Monteith equation with reflectance-based estimates of canopy biophysical variables, such as surface albedo (r), leaf area index (LAI) and crop height (hc). A time series of high spatial resolution RapidEye (REIS), SPOT4 (HRVIR1) and Landsat 8 (OLI) images acquired during the 2012/2013 agricultural season has been used to assess the spatial and temporal variability of crop evapotranspiration ETc and biophysical variables. The validation using the dual crop coefficient approach (Kcb) showed that the satellite-based estimates of daily ETc were in good agreement with ground-based ETc, i.e., R2 = 0.75 and RMSE = 0.79 versus R2 = 0.73 and RMSE = 0.89 for the Kc-NDVI, respective of the analytical approach. The assessment of irrigation performance in terms of adequacy between water requirements and allocations showed that CWR were much larger than allocated surface water for the entire area, with this difference being small at the beginning of the growing season. Even smaller differences were observed between surface water allocations and Irrigation Water Requirements (IWR) throughout the irrigation season. Finally, surface water allocations were rather close to Net Irrigation Water Requirements (NIWR).

Application of the Head-Tail Method to Determine Irrigation Coefficient in Hongguang Irrigation District

Irrigation coefficient is not only a critical criterion of the efficiency of agricultural water use, but also an important basis for the evaluation of regional water-saving scheme. According to the Head-tail method (measured net irrigation water use and gross irrigation water use), the irrigation coefficient of Hongguang irrigation district was determined in this paper. The results showed that this method well fitted the real situation of Hongguang irrigation district, and had several advantages including conceptually clear, convenient to use by local staffs. Practical application of this method in irrigation district provides good reference for the future routine evaluation of irrigation efficiency in irrigation.

Net irrigation water requirements for major irrigated crops with variation in evaporative demand and precipitation in southern Alberta

Weather variability has a profound influence on crop and irrigation water requirements. Estimates of crop evapotranspiration (ETc) and net irrigation water requirements are needed for water allocation, risk management and irrigation system planning. Seasonal ETc and net irrigation water requirement estimates based on the standardized Penman-Monteith method were examined through frequency analysis of historical weather data. Seasonal ETc calculated using the Penman-Monteith equation is based on daily solar radiation, air temperature, relative humidity, and wind speed. Historical weather data from 1983 to 2012 at Lethbridge and Vauxhall were used to determine seasonal ETc, seasonal precipitation and net irrigation water requirements for 11 major (most prevalent) irrigated crops in southern Alberta. Seasonal ETc was consistently greater at Lethbridge than Vauxhall, whereas seasonal precipitation was generally less at Vauxhall than Lethbridge for all major crops. Mean seasonal ETc ranged from 355 mm for barley silage at Vauxhall to 728 mm for alfalfa hay at Lethbridge at a 10% chance of exceedance. Mean net irrigation water requirements ranged from 273 mm for barley silage at Vauxhall to 526 mm for alfalfa hay at Lethbridge at a 10% chance of exceedance. Area-weighted seasonal ETc demand within the irrigation districts is currently about 500 mm (2.8 billion m3) and the net irrigation water requirement within the irrigation districts is at least 380 mm (2.1 billion m3) at a 10% chance of exceedance. Annual gross diversion requirements for the irrigation districts could approach the licensed water allocation limit of 3.45 billion m3 at a 10% chance of exceedance when conveyance losses, irrigation system application efficiencies, and current irrigation management practices are considered. The frequency with which annual gross irrigation water requirements approach or exceed this licensed water allocation limit may increase in the future with climate change in southern Alberta.

Adaptation Technology: Benefits of Hydrological Services—Watershed Management in Semi-Arid Region of India

Watershed management consists of multifunctional activities to manage and address the increasing water resource problems. Ever increasing water demand and rapidly depleting water resources, it has become necessary to develop the adaptation options to recharge groundwater resources. A watershed is a special kind of Common Pool Resources (CPRs); an area is defined by hydrological linkages where optimal management requires coordinating the use of natural resources by public participation. Watershed developments have shown significant positive impacts on water table, perennially of water in wells and water availability especially in semi-arid regions. This paper describes direct and indirect impacts of the watershed activities and benefits of hydrological services dealing with watershed management with future prediction of net irrigation water supply. In the present work, we have also discussed the multiple impacts of watershed of CPRs for improving groundwater and surface water resources.

Simulation of Deep Percolation in Fields with Greater Depth of Groundwater

The rules of deep percolation produced by irrigation under maize in the field with greater depth of groundwater are studied. With the maize cultivation in Dalian as an example, 1-D finite element model is built by VADOSE/W using the daily meteorological data in the years with guaranteed rainfall frequency of 75%, 50% and 25% through analyzing the years-long period regional meteorological data. By this model, the field soil water flow in a whole year under the rain-fed, sprinkler irrigation and border irrigation is simulated respectively, and the water balance of 1m-deep root zone is analyzed. The simulation shows that the ratio of deep percolation to the sum of net precipitation and net irrigation water amount is less than 5% under the rain-fed, 5%~9% under the sprinkler irrigation, 7%~13% under the border irrigation respectively. 70%~95% of deep percolation is produced by irrigation and about 13%~28% of net irrigation water amount is lost as deep percolation, as a result, the main reason for deep percolation can be concluded as irrigation in fields.