Monitoring of Impact of Ferti‐irrigation by Post‐methanated Distillery Effluent on Groundwater Quality

The impact assessment of molasses‐based distillery‐effluent irrigation on groundwater quality around village Gajraula in the district of Jyotiba Phule Nagar, Uttar Pradesh, India was studied by sampling groundwater on monthly intervals consecutively for summer, winter and monsoon seasons during 2006–2007 and water quality parameters, viz. pH, electrical conductivity (EC), chloride (Cl^?), sulphate (SO), nitrate (NO), chemical oxygen demand (COD), total solids (TS), total dissolved solids (TDS), sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), zinc (Zn²⁺), iron (Fe³⁺), and total coliforms (TC) were monitored. Results depicted that the values of all parameters decreased with increasing depth of water table. Sulphate, nitrate and potassium contents were maximal in agricultural site during monsoon while EC, Cl^?, TS, TDS, Na⁺, Ca²⁺, Mg²⁺, Zn, and Fe were maximal in industrial sites during summer. Groundwater samples of residential site harboured maximum coliforms especially during monsoon, highlighting threat to groundwater. Significant positive correlation matrix between coliforms with nitrate, sulphate and potassium ions explained their survival on these nutrients. To overcome this, important measures emphasizing improvement in effluent treatment technology matching site‐specific characteristics are recommended for eco‐friendly ferti‐irrigation.     

Groundwater quality suitable zones identification: application of GIS,Chittoor area,Andhra Pradesh,India

Due to uneven spatial and temporal distribution of rainfall and lack of sufficient water management technologies, the development activities of the society are totally depending on groundwater resources. In addition to the prevailing drought-prone conditions, the improperly treated and unplanned release of effluents of industry, municipal and domestic into the nearby streams and ponds and the majority usage of groundwater for irrigation are increasing the ionic concentration of the groundwater and making it more saline. The analytical results of the collected groundwater samples show that the groundwater is alkaline, and sodium and bicarbonate are the dominant cation and anion, respectively. Gibbs variation diagram shows that the control of the chemistry of groundwater in the study area is the weathering of granitic gneisses and also the leaching of evaporated and crystallized ions from the topsoil of the irrigated areas and improperly treated industrial effluent ponds. GIS, a potential tool for facilitating the generation and use of thematic information, has been applied and analyzed for identification of groundwater quality suitable zones for domestic and irrigation purposes. 30.06% of the area is with suitable, 67.45% of the area is with moderately suitable and 2.45% of the area is with unsuitable quality of groundwater for domestic purpose. 46% of the area is with suitable, 53.36% of the area is with moderately suitable and 0.64% of the area is with unsuitable quality of groundwater for irrigation purpose.     

基于改进SWAT模型的灌溉—施肥—耕作对乌梁素海流域营养物负荷及作物产量的影响

不合理的灌溉、施肥和耕作是导致乌梁素海流域农业面源污染的主要根源,乌梁素海作为我国北方地区重要的生态安全屏障,多年来面临着湖泊水环境污染、水生态退化等问题,科学开展湖泊水环境综合治理首先要解决流域内农业面源污染问题.研究通过修改土壤水平衡、溶质平衡、地下水平衡和作物生长等模块对SWAT 2012原始版本进行改进,并采用改进的SWAT模型构建了乌梁素海流域分布式水文模型,利用实测径流、硝态氮与总磷排放量、地下水埋深以及作物产量校正和验证模型.基于现状情景,以玉米、葵花和小麦3种主要作物为研究对象,设置了削减灌水量、施肥量及调整耕作方式3种农田管理情景.基于改进SWAT模型不同情景的模拟结果,计算分析各管理情景下的硝态氮与总磷负荷及对各作物产量的影响.结果表明,改进SWAT模型具有良好的模拟效果.不同作物削减5%夏灌水量增产最多达8.41%～10.32%,削减10%秋浇水量均明显减少硝态氮和总磷负荷.不同作物营养物负荷均随着氮磷施肥削减比例的增大呈现逐渐降低的趋势,但下降曲线逐渐趋于平缓;各作物产量随氮磷施肥削减比例的增加呈先增加后减少的趋势,其中玉米、小麦氮磷施肥削减比例达20%时产量开...     

Infiltration efficiency in sprinkler irrigation

The term ‘infiltration efficiency’ is proposed to incorporate the losses due to surface runoff in sprinkler irrigation. Infiltration efficiency is calculated analytically using Kostiakov's empirical equation. A dimensionless graph for computing infiltration efficiency and a numerical application of the theory to sprinkler design are also included.     

Use of Sentinel-2 MSI data to monitor crop irrigation in Mediterranean areas

The availability of accurate information on the water consumed for crop irrigation is of vital importance to support compatible and sustainable environmental policies in arid and semi-arid regions. This has promoted several studies about the use of remote sensing data to monitor irrigated croplands, which are mostly based on statistical classification and/or regression techniques. The current paper proposes a new semi-empirical approach that relies on a water balance logic and does not require local tuning. The method stems from recent investigations which demonstrated the possibility of combining standard meteorological data and Sentinel-2 (S-2) Multi Spectral Instrument (MSI) NDVI images to estimate the actual evapotranspiration (ETa) of irrigated Mediterranean croplands. This ETa estimation method is adapted to drive a simplified site water balance which, for each 10-m S-2 MSI pixel, predicts the irrigation water (IW), i.e. the water which is consumed in addition to that naturally supplied by rainfall. The new method, fed with ground and satellite data from two years (2018–2019), is tested in a Mediterranean area around the town of Grosseto (Central Italy), that is covered by a particularly complex mosaic of rainfed and irrigated crops. The results obtained are first assessed qualitatively for some fields grown with known winter, spring and summer crops. Next, the IW estimates are evaluated quantitatively versus ground measurements taken over two irrigated fields, the first grown with processing tomato in 2018 and the second with early corn in 2019. Finally, the IW estimates are statistically analyzed against various datasets informative on local agricultural practices in the two years. All these analyses indicate that the proposed method is capable of predicting both the intensity and timing of the IW supply in the study area. The method, in fact, correctly identifies rainfed and irrigated crops and, in the latter case, accurately predicts the IW actually supplied. The results of the quantitative tests performed on tomato and corn show that over 50 % and 70 % of the measured IW variance is explained on daily and weekly bases, respectively, with corresponding mean bias errors below 0.3 mm/day and 2.0 mm/week. Similar indications are produced by the qualitative tests; reasonable IW estimates are obtained for all winter, springs and summer crops grown in the study area during 2018 and 2019.     

Impact of spatial and temporal aggregation of input parameters on the assessment of irrigation scheme performance

The simulations of dynamic, spatially distributed non-linear models are impacted by the degree of spatial and temporal aggregation of their input parameters and variables. This paper deals with the impact of these aggregations on the assessment of irrigation scheme performance by simulating water use and crop yield. The analysis was carried out on a 7000 ha irrigation scheme located in Southern Spain. Four irrigation seasons differing in rainfall patterns were simulated (from 1996/1997 to 1999/2000) with the actual soil parameters and with hypothetical soil parameters representing wider ranges of soil variability. Three spatial aggregation levels were considered: (I) individual parcels (about 800), (II) command areas (83) and (III) the whole irrigation scheme. Equally, five temporal aggregation levels were defined: daily, weekly, monthly, quarterly and annually.

The results showed little impact of spatial aggregation in the predictions of irrigation requirements and of crop yield for the scheme. The impact of aggregation was greater in rainy years, for deep-rooted crops (sunflower) and in scenarios with heterogeneous soils. The highest impact on irrigation requirement estimations was in the scenario of most heterogeneous soil and in 1999/2000, a year with frequent rainfall during the irrigation season: difference of 7% between aggregation levels I and III was found. Equally, it was found that temporal aggregation had only significant impact on irrigation requirements predictions for time steps longer than 4 months. In general, simulated annual irrigation requirements decreased as the time step increased. The impact was greater in rainy years (specially with abundant and concentrated rain events) and in crops which cycles coincide in part with the rainy season (garlic, winter cereals and olive).

It is concluded that in this case, average, representative values for the main inputs of the model (crop, soil properties and sowing dates) can generate results within 1% of those obtained by providing spatially specific values for about 800 parcels.     

A preliminary assessment of nitrate degradation in simulated soil environments

This study was directed toward a preliminary assessment of nitrate degradation in northeast Iowa soils. Soil experimental plots were created with variable combinations of fertilizers, ethanol, irrigation, and plant growth. The maximum average concentration of nitrate was much higher in the chemically fertilized plots (500 mg/km) than those fertilized organically (120 mg/kg). This was attributed to the excessive ammonia volatilization from the applied cow manure. Soil nitrate dropped from 155 to 50 mg/kg in a matter of 3 weeks in the deep samples of the intermittently irrigated plots. This is because higher soil moisture lowered the oxygen level, which favored denitrification. Although ethanol seemed to have restricted the release of nitrate in the manure-treated plots, the data are not conclusive. The highest degradation of soil-nitrate (lowest recovered 38 mg/kg) was observed in the plots that simultaneously grew corn, received cow manure, and were not irrigated. Soils in these plots were depleted of nitrogen by ammonia volatilization from manure, and through the uptake by corn plants. Nitrification of organic nitrogen to nitrate was restricted in plots that were left without irrigation. Rain events helped nitrification on the surface, but promoted denitrification at depth.     

河套灌区耕地-荒地-海子系统间不同类型水分运移转化

为了探明耕地-荒地-海子系统中不同类型水分的运移转化规律,在2018-2019年典型时期对系统内具有代表性的采样点进行水样采集,分析了不同时期内不同水体的δ¹⁸O变化特征,并利用二端元混合模型和土壤水动力学方法计算了不同类型水分转化贡献率。结果发现：①在灌溉期,82%的灌溉水储存于1 m土体中,18%的灌溉水通过渗漏补给了耕地地下水,渠系灌溉水通过地下侧向径流给耕地地下水贡献了76%。②灌溉水和降雨对耕地地下水平均贡献率为94%和6%;耕地地下水和降雨对荒地地下水的平均贡献率为71%和29%;荒地地下水和降雨对海子的平均贡献率为43%和57%。③渠系灌溉水通过侧向径流贡献给耕地地下水的水量基本全部迁移给了荒地地下水,地下水迁移转化是由渠系水侧向径流触发的。④灌后5 d,耕荒地交界土层0~40 cm存在饱和-非饱和侧向补给;灌后15 d和30 d,耕地和耕荒地交界处的地下水向根区40~60 cm、土层80 cm以及100 cm补给水分;灌后30 d,耕地中的灌溉水水分消失。⑤在非灌溉期,荒地地下水和海子耗水较多,应给海子补给水分。     

Implications of climate change for sustainable water resources management in India

This paper presents an overview of the current water resources scenario in India, and recent work carried out in India to assess the climate change impact on hydrology and water resources. Issues that need to be addressed with respect to climate change/variability in sustainable water resources planning and management are discussed.     

The impact of freshwater and wastewater irrigation on the chemistry of shallow groundwater: a case study from the Israeli Coastal Aquifer

Differences in the impact of irrigation with freshwater versus wastewater on the underlying shallow groundwater quality were investigated in the Coastal Aquifer of Israel. Seven research boreholes were drilled to the top-most 3–5 m of the saturated zone (the water table region-WTR) in the agricultural fields. The unsaturated zone and the WTR below the irrigated fields consist mainly of clayey sands, while the main aquifer comprises mainly of calcareous sandstones and sands. We show that the salinity and composition of the groundwater at the WTR are highly variable over a distance of less than 1 km and are controlled by the irrigating water and the processes in the overlying unsaturated zone. Tritium data in this groundwater (4.6 tritium units (TU)) support that these water are modern recharge. The water at the WTR is more saline and has a different chemical composition relative to the overlying irrigation water. High SAR values (sodium adsorption ratio) in wastewater irrigation lead to absorption of Na⁺ onto the clay and release of Ca²⁺ into the recharging water, resulting in low Na/Cl (0.4 compared to 1.2 in the wastewater) and high Ca/Cl ratios. In contrast, in the freshwater-irrigated field the irrigation water pumped from the aquifer (Na/Cl=0.9; SAR=0.6) is modified into Na-rich groundwater (Na/Cl=2.0) due to reverse base-exchange reactions. The high NO₃ concentration (>100 mg/l) in the WTR below both fields is derived from the agricultural activities. In the freshwater field, the source of NO₃ is fertilizer leachates, whereas in the wastewater field, where less fertilizers are applied, nitrate is probably derived from nitrification of the NH₄ in the wastewater. Some of the original inorganic nitrogen in the wastewater is consumed by the agricultural plants, resulting in a lower inorganic-N/Cl ratio in the WTR as compared to that in the wastewater. This study demonstrates the important role of the composition of irrigation water, combined with lithology and land use, in determining the quality of the water that recharge the aquifer below agricultural fields.