Water Table Decline Research Articles

Irrigation Management Strategies to Increase Crop-Water Productivity and Grain Quality of Direct Seeded Rice in North West IGP: A Review

Due to its great productivity and profitability, rice (Oryza sativa L.) is farmed in alluvial irrigated tracts of northwest India. For half of the world's population as well as in our country, rice serves as the main source of calories. However, excessive groundwater use in rice farming has resulted in an alarming decline in water table, indicating overuse of groundwater. Therefore, it is necessary to investigate alternative, resource-conserving methods that can sustain rice production. Direct seeded rice presents a compelling option when the future of rice production is in jeopardy due to worldwide water constraint and rising labour costs. The oldest method of crop establishment in this regard, direct seeded rice (DSR), is becoming more and more well-liked constraints minimal input requirements. It has certain benefits, including labour savings, a reduction in water and manpower requirements, early crop maturity, cheap production costs, improved soil physical conditions for crops, a reduction in methane emissions, and greater options for being the best match in various cropping systems. For dry-seeded rice, management strategies that cut irrigation water use and boost crop-water production are needed. Some of the interventions in this respect include cultivars with short growing seasons, tillage, and irrigation scheduling. High crop-water productivity is ensured with optimal yields thanks to irrigation scheduling that aims to eliminate over- or under-irrigation. Tillage changes the edaphic environment of the soil, which impacts crop development. Because of their shallow root systems, rice plants are unable to use the water in the deeper layers of the soil. In order to increase the deep root growth of rice cultivars, deep tillage has become the preferable method. The present research evaluates irrigation management options to raise crop-water productivity and grain quality of DSR in northwest IGP based on the available evidence.

Direct Seeded Rice as Resource Efficient Technology

In Asia, seedlings are typically transplanted into puddled soil to cultivate rice (Oryza sativa L.). Due of the manpower, water, and energy requirements of this manufacturing system, it is becoming less lucrative as these resources become more scarce. Additionally, it impairs the soil's physical qualities, negatively impacts the performance of succeeding upland crops, and increases methane emissions. Different issues, such as a declining water table, a manpower shortage during peak seasons, and worsening soil quality, need the use of alternate establishment techniques to maintain both natural resource and rice yield. Due to its low input requirement, ability to reduce greenhouse gas emissions, and ability to adjust to climatic hazards, the direct seeded rice (DSR) technique has gained a lot of attention and popularity in recent years. Dry seed must be sown into a ready seedbed, while pre-germinated seed must be sown into standing water and puddles of soil. Many farmers have switched from transplanted to DSR culture as a result of the introduction of early maturing cultivars, the application of effective fertiliser management techniques, and increased adoption of integrated weed management strategies. In certain industrialised nations, such the USA, Australia, Japan, China, and Korea, DSR technology is heavily mechanised. By switching from conventional rice to DSR, crop water requirements, soil organic matter turnover, improved nutrient management, carbon sequestration, weed management, greenhouse gas emissions, and crop intensification will all be significantly reduced. The transition from PTR to DSR is hampered by a number of factors, including a high weed infestation, the development of weedy rice, an increase in soil-borne diseases (nematodes), nutritional disorders, poor crop establishment, lodging, the prevalence of blast, brown leaf spot, etc. By addressing these limitations, DSR may show to be a very viable, economically and technically viable substitute for PTR.

Drawdown‐induced consolidation of aquifer systems considering water‐table decline

AbstractBoundary condition is an important factor in estimating land subsidence induced by groundwater withdrawal. In previous analytical studies, the upper boundaries are commonly assumed to be constant‐head, which could fail to reflect the declines in groundwater table during groundwater pumping. A one‐dimensional (1‐D) consolidation model of aquifer systems due to groundwater drawdown is considered in this study, in which the water‐table decline is taken into account. A mathematical model, which incorporates Neuman's model of unconfined flow into Terzaghi's theory of consolidation, is first presented. The analytical solutions for both hydraulic head drawdown and subsidence are developed in the Laplace domain. A more explicit solution to the elastic, single‐layered model is also derived. The validation of the presented solutions is verified by comparing with existing solutions in degenerated cases. The results show that the presented hydraulic drawdown solutions can be used to describe the water table decline. Moreover, the subsidence solutions are notably different from solutions based on the commonly‐used constant‐head boundary, and these previous models could severely underestimate the subsidence. The influences of specific yield, compressibility of the pore water, hydraulic conductivity, and viscosity of soil skeleton on the water table decline and long‐term deformation are also investigated using the presented solutions.

Partitioning and sourcing of evapotranspiration using coupled MARMITES-MODFLOW model, La Mata catchment (Spain)

The new, two-way coupled, distributed and transient MARMITES-MODFLOW (MM-MF) model, coupling land surface and soil zone domains with groundwater, is presented. It implements model-based partitioning and sourcing of subsurface evapotranspiration (ETss) as part of spatio-temporal water balance (WB). The partitioning of ETss involves its separation into evaporation (E) and transpiration (T), while the sourcing of E and T involves separation of each of the two into soil zone (Esoil and Tsoil) and groundwater (Eg and Tg) components. The objective of that development was to understand the system dynamics of a catchment with shallow water table, through spatio-temporal quantification of water fluxes and evaluation of their importance in water balances, focusing on the Eg and Tg components of ETss. While the Eg is computed using formulation from published study, the Tg is obtained through a novel phenomenological function, based on soil moisture availability and transpiration demand driven by climatic conditions. The MM-MF model was applied in the small La Mata catchment (~4.8 km2, Salamanca Province, Spain), characterized by semi-arid climate, granitic bedrock, shallow water table and sparse oak woodland. The main catchment characteristics were obtained using remote sensing, non-invasive hydrogeophysics and classical field data acquisition. The MM-MF model was calibrated in transient, using daily data of five hydrological years, between 1st October 2008 and 30th September 2013. The WB confirmed dependence of groundwater exfiltration on gross recharge. These two water fluxes, together with infiltration and Esoil, constituted the largest subsurface water fluxes. The Eg was higher than the Tg, which is explained by low tree coverage (~7%). Considering seasonal variability, Eg and Tg were larger in dry seasons than in wet season, when solar radiation was the largest and soil moisture the most depleted. A relevant observation with respect to tree transpiration was that during dry seasons, the decline of Tsoil, associated with the decline of soil moisture, was compensated by increase of Tg, despite continuously declining water table. However, in dry seasons, T was far below the atmospheric evaporative demand, indicating that the groundwater uptake by the tree species of this study constituted a survival strategy and not a mechanism for continued plant growth. The presented MM-MF model allowed to analyze catchment water dynamics and water balance in detail, accounting separately for impacts of evaporation and transpiration processes on groundwater resources. With its unique capability of partitioning and sourcing of ETss, the MM-MF model is particularly suitable for mapping groundwater dependent ecosystems, but also for analyzing impacts of climate and land cover changes on groundwater resources.

Development and Application of a Methodology for the Identification of Potential Groundwater Recharge Zones: A Case Study in the Virvini Micro-Basin, Tiraque, Bolivia

Groundwater plays a vital role in human consumption and irrigation in many parts of Bolivia; yet, the absence of policies to regulate its extraction and protect groundwater recharge areas has led to a decline in water tables and threatened food security. Some municipal initiatives have been implemented to develop regulations, but the lack of reliable hydrogeological data (such as aquifer geometry, groundwater level data, location of potential groundwater recharge zones, and flow dynamics) hinders their effective implementation. The case study presented herein focuses on a municipal policy in Tiraque, Bolivia, aimed at protecting groundwater recharge zones, in addition to the need for a reliable methodology for their technical identification. The EARLI approach (an acronym for “Enhanced Algorithm for Recharge based on the Rainfall and Land cover Inclusion”) is suggested as a participatory-simplified multi-criteria decision method to address the absence of hydrogeological data. This approach was adjusted to the basin’s specific conditions, including local vegetation communities and their influence on infiltration, and was applied as a pilot study in the Virvini micro-basin. The EARLI model emphasizes the spatial distribution of rainfall as an input indicator for potential recharge in addition to the biophysical characteristics of the catchment area. The methodology successfully mapped the degree of groundwater recharge potential and was validated by traditional hydrogeological models, field infiltration measurements, and the local community’s application of the tool. Therefore, the results of this study provide the necessary technical bases for groundwater-integrated management in Tiraque.

Hydrological dynamics and associated greenhouse gas fluxes in a mountain peatland under different climate scenarios

AbstractPeatlands have sequestered atmospheric carbon dioxide (CO2) for millennia and can also act as significant sources of atmospheric methane (CH4). Hydrological processes that control water table dynamics, and climatic conditions such as air temperature, play important roles in mediating peatland–atmosphere exchange of these greenhouse gases. These controls are likely to be impacted by climate change, particularly for those peatlands found in cold environments, including mountain regions. In this study, we developed empirical models to simulate hydrological dynamics and ecosystem–atmosphere C exchange in a mountain peatland under three climate scenarios (2012 air temperatures, +2°C and +4°C). Observed water table dynamics and air temperature were used to model ecosystem–atmosphere C exchange during the 2012 growing season. Modelled snowmelt dynamics were used to predict water table position at the beginning of the growing season for warming scenarios, and the subsequent water table dynamics and increased air temperature were used to drive the same C exchange models during the growing seasons. Increased air temperatures led to earlier snowmelt and water table decline, causing water tables to drop by 10 and 19 cm for the +2 and +4°C scenarios, respectively. This led to roughly a two‐fold decrease in growing season net ecosystem production (NEP) in both warming scenarios, as a result of increased ecosystem respiration relative to gross primary production. Methane efflux was positively correlated with NEP and therefore decreased under the warming scenarios, albeit to a lesser degree. These results indicate that reductions in NEP and CH4 efflux are possible in low‐elevation mountain peatlands that are dependent on snowpack‐derived hydrologic inputs. These ecosystems are found at elevations where future winter precipitation will increasingly fall as rain rather than snow and melting of snowpack will occur earlier under warmer conditions.

Impacts of urbanization, LULC, LST, and NDVI changes on the static water table with possible solutions and water policy discussions: A case from Islamabad, Pakistan

Rapid urbanization, coupled with land use land cover changes (LULC), has caused stress on freshwater resources around the globe. As in the case of Islamabad, the capital of Pakistan, the population has increased significantly, creating a deficit of natural resources and affecting the environment adversely. Therefore, the purpose of this study is to examine the effects of urbanization and LULC on the decline of the static water table in Islamabad. It also seeks to analyze water policy issues in order to achieve sustainable water resource development. The excessive pumping of the existing groundwater has exceeded the safe limit, which is justified by the constantly growing population. However, the changes in the LULC of the study area have turned many green pastures into barren land. Our research data were obtained from the Capital Development Authority (CDA), Pakistan Meteorological Department (PMD), and Landsat Satellite images. After analyzing PMD and CDA data for the last 20 years (2000–2020), the results were interpreted using Arc GIS. It has been observed that the Normalized Difference Vegetation Index (NDVI) value increases as the Land Surface Temperature (LST) decreases. Therefore, the overall observation is a decreasing trend in Islamabad temperatures due to the increased vegetation in the study area during the period of 2000–2020. It was observed that there has been a considerable drop in water levels due to over-pumping in a few areas. It is primarily associated with the increasing population of the capital in the last 2 decades. This study uses a survey to explore the potential locations for check dams to enhance and recharge the groundwater aquifers in the capital, Islamabad. It suggests catchment areas throughout the Margalla Hills along with different localities, such as Rumli Village, Trail 5, and Shahdara.

Effect of vapour transport on soil evaporation under different soil textures and water table depths in an arid area of Northwest China

AbstractIn arid area, the liquid water and water vapour states in soil profiles and fluxes at the upper and bottom interfaces are extremely complex due to heterogeneity of soil textures and the driving forces of heat and matrix potential. In this study, we used Hydrus‐1D to simultaneously simulate liquid water, water vapour, and heat transport based on the observed datasets of atmosphere, soil and groundwater at three soil profiles in an arid area of northwest China. Based on the comparison of the observed and simulated results at the three soil profiles, we show that there are diurnal vapour entry and outlet fluxes at the dry surface layer of 30 cm in the summer season. The vapour entry and re‐evaporation account for about 14% of annual precipitation for the heterogeneity soil profile with a mean groundwater depth of 210 cm. Because of limited soil moisture in this arid area, vapour induced re‐evaporation occurs shortly in the early daytime. Moreover, the extent of vapour entry, condensation and re‐evaporation are strongly dependent on soil properties and water table depth. The deeper water table produces the drier soil surface, allowing more vapour entry, condensation and re‐evaporation. Whereas the finer grained soil layers benefit the vapour fixation to produce zero fluxes that substantially inhibit the upward liquid water and vapour fluxes, and thereby reduces soil actual evaporation (AE). The reduced AE correspondingly decreases the capillary effect on phreatic evaporation, given that AE decreases slowly with decline of water table and the large extinct depth of phreatic evaporation for the finer grained soil profiles. The estimated extinct depths are 180 and 200 cm for the soil profiles consisting of silt loam and loamy sand, respectively, much larger than 100 cm of the typical sandy soil profile. Additionally, as water table is comparably higher and lower than the extinct depth, the models neglecting the vapour – heat function could, respectively, overestimate and underestimate soil evaporation.

An Investigation of Recharging Groundwater Levels through River Ponding: New Strategy for Water Management in Sutlej River

Groundwater is an essential water resource in the current era, and studying its sustainability and management is highly necessary nowadays. In the current area of research interest, the reduced mean annual Sutlej River flow, the increase in the population/built-up areas, and enhanced groundwater abstractions have reduced groundwater recharge. To address this issue, groundwater recharge modeling through ponding of the Sutlej River was carried out using a modular three-dimensional finite-difference groundwater flow model (MODFLOW) in a 400 km2 area adjacent to Sutlej River. The mean historical water table decline rate in the study area is 139 mm/year. The population and urbanization rates have increased by 2.23 and 1.62% per year in the last 8 years. Domestic and agricultural groundwater abstraction are increasing by 1.15–1.30% per year. Abstraction from wells and recharge from the river, the Fordwah Canal, and rainfall were modeled in MODFLOW, which was calibrated and validated using observed data for 3 years. The model results show that the study area’s average water table depletion rate will be 201 mm/year for 20 years. The model was re-run for this scenario, providing river ponding levels of 148–151 m. The model results depict that the water table adjacent to the river will rise by 3–5 m, and average water table depletion is expected to be reduced to 151 to 95 mm/year. The model results reveal that for ponding levels of 148–151 m, storage capacity varies from 26.5–153 Mm3, contributing a recharge of 7.91–12.50 million gallons per day (MGD), and benefiting a 27,650–32,100-acre area; this means that for areas benefitted by dam recharge, the groundwater abstraction rate will remain sustainable for more than 50 years, and for the overall study area, it will remain sustainable for 7–12.3 years. Considering the current water balance, a recharging mechanism, i.e., ponding in the river through the dam, is recommended for sustainable groundwater abstraction.

Determinants of Climate Change Adaptation Strategies in Bundelkhand Region, India

The study attempted examining climate change adaptation strategies in the most backward regions of India, i.e., the Bundelkhand region. Data were collected from 200 farmers during April and May of 2017, and a binary logistic regression model was used to analyze the data. The farmers were most likely to improve irrigation facilities if they have access to institutional credit, information about the weather, and have taken crop insurance. Also, farmers perceived that an increase in temperature, a decline in rainfall, and a decline in water tables motivate and influence farmers to change their cropping pattern from wheat (a water-intensive crop) to chickpea (a less water-intensive crop) to cope with the changing climate. Hence, the present study recommends that since water table is declining continuously and creating water crisis even in the rainy season for agriculture and domestic consumption, community participation in the conservation of water-bodies is vital. Further, the adoption of crop varieties that require less water, are drought tolerant and mature early will help increase farm productivity and reduce cultivation costs. Lastly, an advance regional weather forecasting system capable of providing farmers with accurate information that will enable them to change cropping patterns and adjust farming practices are required.

Spatio-Temporal Evolution of the Ecological Environment in a Typical Semi-Arid Region of Northeast China

Increasing trends of groundwater and soil salinization, as well as desertification, is characteristic of many arid and semi-arid regions under climatic and anthropogenic influences. This has led to the implementation of management strategies to protect the ecological environment. Changling County in Northeast China is a typical semi-arid area that has experienced these changes. Thus, management strategies such as the “Three North Shelterbelt Project” which involves planting trees to reduce wind speed and halt desertification, and the Changling local alkaline land restoration project, from the year 2000, involving fencing of grasslands have been implemented in the area. Premised on the dynamic nature of the ecological environmental problems, this study was undertaken to assess the spatio-temporal evolution of the ecological environment using hydro-geochemical, spatial, remote sensing, and statistical techniques from the year 2001 to 2019. It was found that groundwater salinity was stable within the period due to groundwater exploitation that declined depth to groundwater table (DWT) thus reducing the impact of evaporation concentration of salts in groundwater. Salinized land area increased by about 6706 ha at a rate of 0.06%/year as a result of the reduction in the size of water bodies and swampland as the declining water table exposed shallow water to more evaporation. The effect of the conversion of water bodies and swamplands to salinized land is believed to overshadow the climatic influence of decreased evaporation-precipitation ratio that normally decreases soil salinization. Most of the study area was stable in terms of desertification (98.22%, 56,3497 ha) as significantly degraded lands covered only 0.03% (148 ha) of the area while 1.67% (9556 ha) had significantly increased vegetation, respectively. Precipitation had an insignificant relationship with desertification with irrigation believed to be the main driver of significant vegetation improvement. Water-saving irrigation practices and the growing of salt-tolerant or semi-tolerant crop species are recommended to maximize food production while stemming the environmental degradation trend due to declining DWT.

Sustainable Sugarcane Initiative- The Saviour of Sugarcane Sector

Sugarcane, a crop that has a huge impact on the livelihood of many farmers and sugar industries in the world. In India, about 50 million farmers depend on sugarcane yield which is about 7.5% of the village population. India has more than 538 sugar mills produces 32.93 million tons of sugar, jaggery, and its by products like Molasses, Bagasse etc. But due to the various issues like erosion in flooded soil which leads to the nutrients leaching, declining water table due to the erratic monsoon and increase in cultivation cost and steady yield (productivity stable as about 65-70 tons/hectare), a new technology is essential to meet future demands. Sustainable Sugarcane Initiative (SSI) is a method of sugarcane cultivation whose main purpose is to enhance sugarcane production by greater input use efficiency. SSI involves the use of less seeds, less water and optimum usage of fertilizers and manures with wider spacing thus leads to more productivity( more than 40% than present), efficient water usage (more than 40% than present) ,more profit (more than 30% than present).

Sustainable management of groundwater extraction: An Australian perspective on current challenges

Study regionAustralia Study focusOur incomplete knowledge of groundwater systems and processes imposes barriers in attempting to manage groundwater sustainably. Challenges also arise through complex institutional arrangements and decision-making processes, and the difficulty in involving stakeholders. In some areas, these difficulties have led to water table decline and impacts on groundwater users and groundwater-dependent ecosystems. However, there is potential to improve the sustainable use of groundwater resources through improvements in management practices. We discuss some of the challenges, and present survey results of research, government, and industry professionals across the groundwater sector in Australia. New hydrological insights for the regionThe highest-ranked challenge identified in the survey was the difficulty in determining regional-scale volumetric water extraction limits. This is surprising given the criticism in the international literature of volumetric based approaches for groundwater management, and the decreased reliance on this approach in Australia and elsewhere in recent years. Other major challenges are the difficulty in determining and implementing maximum drawdown criteria for groundwater levels, determining water needs of ecosystems, and managing groundwater impacts on surface water. Notwithstanding these gaps in technical understanding and tools and a lack of resources for groundwater studies, improvements in stakeholder communication should enable more effective decision-making and improve compliance with regulations designed to protect groundwater and dependent ecosystems.

A globally robust relationship between water table decline, subsidence rate, and carbon release from peatlands

Peatland ecosystems are globally important carbon stores. Disturbances, such as drainage and climate drying, act to lower peatland water table depths, consequently enhancing soil carbon release and subsidence rates. Here, we conduct a global meta-analysis to quantify the relationship among water table depth, carbon release and subsidence. We find that the water table decline stimulated heterotrophic, rather than autotrophic, soil respiration, which was associated with an increase in subsidence rate. This relationship held across different climate zones and land uses. We find that 81% of the total annual soil respiration for all drained peatlands was attributable to tropical peatlands drained for agriculture and forestry and temperate peatlands drained for agriculture. Globally, we estimate that, drained peatlands release 645 Mt C yr–1 (401–1025 Mt C yr–1) through soil respiration, equivalent to approximately 5% of global annual anthropogenic carbon emissions. Our findings highlight the importance of conserving pristine peatlands to help mitigate climate change.

Water Security in South Asian Cities: A Review of Challenges and Opportunities

Achieving water security in South Asian cities will require a realistic and holistic understanding of the challenges that are growing in extent and severity. These challenges include the rapid rise in urban household water demand due to both overall population growth and increasing urbanization rate. Additionally, surface water supply in closed river basins is fully utilized, and there is little opportunity in these regions to increase the extraction of surface water to meet rising demands. Furthermore, groundwater extraction in most regions exceeds natural recharge rates, leading to rapidly falling annual water tables and seasonal depletion in hard rock regions and to gradually declining water tables requiring deeper wells and increased pumping effort in alluvial regions. Additionally, even in cities with abundant water resources, poorer segments of the population often face economic water scarcity and lack the means to access it. Nevertheless, there are important potential engineering opportunities for achieving water security in South Asian cities. Much withdrawn water is lost due to urban water distribution inefficiency, and a range of proven techniques exist to improve distribution. Metering of urban water can lead to structural improvements of management and billing, though the water needs of the poorest city residents must be ensured. Industrial water-use efficiency can be significantly improved in manufacturing and electricity generation. The quantities of wastewater generated in South Asia are large, thus treating and reusing this water for other purposes is a strong lever in enhancing local water security. There is limited potential for rooftop rainwater harvesting and storage, though capture-enhanced groundwater recharge can be important in some areas. Some individual inter-basin transfer projects may prove worthwhile, but very-large-scale projects are unlikely to contribute practically to urban water security. Overall, the water challenges facing South Asian cities are complex, and although no single intervention can definitively solve growing problems, numerous actions can be taken on many fronts to improve water security.

Water Quality Assessment Bias Associated with Long-Screened Wells Screened across Aquifers with High Nitrate and Arsenic Concentrations.

Semi-arid regions with little surface water commonly experience rapid water table decline rates. To hedge against the falling water table, production wells in central Mexico are commonly installed to depths of several hundred meters below the present water table and constructed as open boreholes or perforated casings across their entire length. Such wells represent highly conductive pathways leading to non-negligible flow across chemically distinct layers of an aquifer—a phenomenon known as ambient flow. The objectives of this study were to estimate the rate of ambient flow in seven production wells utilizing an end-member mixing model that is constrained by the observed transient chemical composition of produced water. The end-member chemical composition of the upper and lower layers of an urban aquifer that overlies geothermal heat is estimated to anticipate the future quality of this sole source of water for a rapidly growing urban area. The comprehensive water chemistry produced by seven continuously perforated municipal production wells, spanning three geologically unique zones across the city of San Miguel de Allende in Guanajuato State, was monitored during one day of pumping. The concentration of conservative constituents gradually converged on steady-state values. The model indicates that, relative to the lower aquifer, the upper aquifer generally has higher specific conductance (SC), chloride (Cl), nitrate (NO3), calcium (Ca), barium (Ba) and magnesium (Mg). The lower aquifer generally has a higher temperature, sodium (Na), boron (B), arsenic (As) and radon (Rn). Ambient flow ranged from 33.1 L/min to 225.7 L/min across the seven wells, but this rate for a given well varied depending on which tracer was used. This new 3D understanding of the chemical stratification of the aquifer suggests that as water tables continue to fall, concentrations of geothermally associated contaminants of concern will increase in the near future, potentially jeopardizing the safety of municipal drinking water.

Response of spring wetlands to restored aquifer pressure in the Great Artesian Basin, Australia

The decline in aquifer water tables resulting from groundwater extraction and the impacts on spring ecosystems is a recurring management issue throughout the world. This study from the Great Artesian Basin in Australia demonstrates how water extraction through uncapped (open) bores since the late nineteenth century has reduced aquifer pressure, dewatering many natural springs. Flow rates to one spring complex at Pelican Creek also declined, but an extraordinary array of endemic species have persisted. At Pelican Creek an extremely rare endemic fish, the red-finned blue-eye (Scaturiginichthys vermeilipinnis) is threatened with extinction from predation by an exotic fish gambusia (Gambusia holbrooki). A government-funded program to cap flowing bores and to replace the distribution of groundwater through open drains with polyethylene pipe has resulted in the partial restoration of aquifer pressure coinciding with the expansion of spring wetlands. The restoration of springs enhances habitat for spring-dependent endemic species, but also makes the removal of gambusia more difficult and the opportunities for dispersal into the few remaining springs free of gambusia more likely. The documentation of the decline in aquifer pressure and loss of springs, followed by pressure recovery with aquifer management, and local management of springs provides lessons for the parallel circumstances throughout the globe.

Groundwater potential and recharge zones mapping using remote sensing and GIS for Kadegaon Taluka, Maharashtra, India

Year by year the water is becoming the scare source all over the world. Water resources available on earth are in the two forms namely surface water and ground water. According to the study of scientist the total volume of the ground water is very less as compared to the total water available in the globe. There are many areas in our country that are facing scarcity of water, and this is due to the no proper planning of the ground water development, results in the fall of water levels, drying of wells, etc. The over exploration of ground water in certain parts of the country may also leads in the lowering of ground water table, and this requires the scientific resource management and conservation. The source of water available below the surface of earth and that can be used as the prime source of water for water supply system majorly for agriculture, and also used for domestic and commercial uses. Groundwater has crucial importance and value for human life and economic development. The ground water has major contribution in the earth’s water circulatory system known as hydrologic cycle.Keeping in mind the growing rate of the population and as result of it the needs of the society could not be satisfied by the available surface water resources. Thus the man has started massive search of water resources. Such massive mining of ground water has leads to drastic decline of ground water table. Thus the ground water has become the precious resources for the agriculture and domestic use. Hence in order to ensure a sensible use of ground water the proper evaluation and management is required.

Groundwater depletion in Haryana: A challenge

India is the world’s largest user of groundwater with over 80% of the rural and urban domestic water consumption met by available groundwater, but every year the water table is depleting in different states of the country. There are total 141 blocks in Haryana, out of which 86 blocks (61% of the state’s geographical area) had reached the red zone due to groundwater exploitation. In year 2004, 55 blocks were under the red category zone, which means that 31 more blocks have come under the distressed category in a decade and a half. The depletion in the water table is now a cause of concern in 14 of the 22 districts of Haryana and mainly Ambala, Kurukshetra, Kaithal, Karnal and Panipat are the worst affected. In the absence of adequate surface water quantity, groundwater has become the main sources of irrigation in the state and the total geographical area of Haryana is 44,212 Sq. Km and out of which cultivable area 36,760 Sq. Km (83.15%). The total area under under irrigation is 2974000 ha (81%) i.e. by Canals 11,53000 ha (38.80%) and by tube wells 18,2100 ha (61.20%). Net Area Irrigated is 29,740 Sq. Km. This has resulted into excessive exploitation of groundwater resources. The indiscriminate withdrawal of groundwater has created a declining water table situation in the state. The average rate of decline over the last 48 years has been about 24 cm per year. In addition, fourteen districts out of twenty two have been categorized as over exploited. This paper, therefore, attempts to analyze the problem of declining water table, factors for its depletion and suitable mitigation measures to combat the declining water table problem for sustainable agriculture development in the state.

Agronomic and Environmental Determinants of Direct Seeded Rice in South Asia.

Rice (Oryza sativa L.) is the staple food of more than 50% of the world’s population. Manual puddled transplanted rice (PTR) system is still the predominant method of rice establishment. However, due to declining water tables, increasing water scarcity, water, labor- and energy-intensive nature of PTR, high labor wages, adverse effects of puddling on soil health and succeeding crops, and high methane emissions, this production system is becoming less profitable. These factors trigger the need for an alternative crop establishment method. The direct-seeded rice (DSR) technique is gaining popularity because of its low input demand compared to PTR. It is done by sowing pre-germinated seeds in puddled soil (wet-DSR), standing water (water seeding), or dry seeding on a prepared seedbed (dry-DSR). DSR requires less water and labor (12–35%), reduces methane emissions (10–90%), improves soil physical properties, involves less drudgery and production cost (US$9–125 per hectare), and gives comparable yields. Upgraded short-duration and high-yielding varieties and efficient nutrient, weed, and resource management techniques encouraged the farmers to switch to DSR culture. However, several constraints are associated with this shift: more weeds, the emergence of weedy rice, herbicide resistance, nitrous oxide emissions, nutrient disorders, primarily N and micro-nutrients, and an increase in soil-borne pathogens lodging etc. These issues can be overcome if proper weed, water, and fertilizer management strategies are adopted. Techniques like stale bed technique, mulching, crop rotation, Sesbania co-culture, seed priming, pre-emergence and post-emergence spray, and a systematic weed monitoring program will help reduce weeds. Chemical to biotechnological methods like herbicide-resistant rice varieties and more competitive allelopathic varieties will be required for sustainable rice production. In addition, strategies like nitrification inhibitors and deep urea placement can be used to reduce N2O emissions. Developing site and soil-specific integrated packages will help in the broader adoption of DSR and reduce the environmental footprint of PTR. The present paper aims to identify the gaps and develop the best-bet agronomic practices and develop an integrated package of technologies for DSR, keeping in mind the advantages and constraints associated with DSR, and suggest some prospects. Eco-friendly, cost-effective DSR package offers sustainable rice production systems with fewer resources and low emissions.Graphical abstract