Area Of Irrigated Land Research Articles

Sustainability of Mediterranean irrigated agro-landscapes

In this work we show the feasibility of empirical testing of socio-environmental models with a relatively simple model of a traditional agro-ecosystem: the Huerta Murcia (Spain). This Mediterranean traditional irrigated land is based on adaptive strategies of irrigation and crop management and has important functions for the conservation of natural and cultural resources. During the last decades, this agro-landscape has been threatened by several factors linked to low profitability of agricultural production under present conditions, the emergence of new irrigated lands outside the river valleys and the land conversion to non-agricultural uses. A dynamic system model has been built to analyse all these processes. Results obtained for the 1932–1995 calibration period show that the model successfully tracks the observed data series for the available variables (area of traditional irrigated lands, number of landowners, population, average farm size and water pollution) and that the Huerta had lost more than 2000ha, explained by competition for land use and the decreasing profitability of farming due to the reduced farm size, the appearance of water deficit and the increasing water pollution. After model testing, including dimensional consistence tests, sensitive analysis and extreme condition tests, a set of policy scenarios (1995–2025) were explored. Land planning policies seem to be more effective than agricultural policies. Then, the observed actual behaviour (1995–2008) of Huerta Murcia was compared to results expected under the analysed scenarios results show an actual rate of loss of Huerta (1995–2008) higher than expected under the base trend (business as usual) scenario. This accelerated loss can be explained by the successive changes in the Municipal Urban Plan, leading to a notable increase in buildable area and to increasing expectations about population growth. When the actual scenario (1995–2008) is implemented by updating exogenous variables or forcing inputs and introducing the potential (virtual) population increase, as derived from the plans, the model is able to predict the whole set of 1995–2008 observed data series with no further calibration against data. This might be considered as a sort of model validation with an independent dataset, which constitutes a remarkable contribution in the area of socio-ecological modelling.

India's Women-led Vegetable Cultivation Improves Economic and Environmental Sustainability

India's food security is heavily dependent on irrigation, yet large rural areas of irrigated land are threatened by increasing salinity and decreasing ground water resources. Therefore, the Johannesburg Plan of Implementation agreed at the World Summit on Sustainable Development in 2002 gives importance to sustainable rural development in developing countries. The plan mandates socio-economic development within the carrying capacity of local ecosystems. One way to increase food productivity is to encourage agriculture-based vegetable cultivation often practiced by women farmers. This paper presents data on the role of tribal women-led organic vegetable farming, which improves the livelihoods of women while enhancing environmental sustainability across India's drylands.

Hydrological responses to climate change conditioned by historic alterations of land-use and water-use

Abstract. This paper quantifies and conditions expected hydrological responses in the Aral Sea Drainage Basin (ASDB; occupying 1.3% of the earth's land surface), Central Asia, to multi-model projections of climate change in the region from 20 general circulation models (GCMs). The aim is to investigate how uncertainties of future climate change interact with the effects of historic human re-distributions of water for land irrigation to influence future water fluxes and water resources. So far, historic irrigation changes have greatly amplified water losses by evapotranspiration (ET) in the ASDB, whereas 20th century climate change has not much affected the regional net water loss to the atmosphere. Results show that errors in temperature (T) and precipitation (P) from single GCMs have large influence on projected change trends (for the period 2010–2039) of river runoff (R), even though the ASDB is spatially well resolved by current GCMs. By contrast, observed biases in GCM ensemble mean results have relatively small influence on projected R change trends. Ensemble mean results show that projected future climate change will considerably increase the net water loss to the atmosphere. Furthermore, the ET response strength to any future T change will be further increased by maintained (or increased) irrigation practices, which shows how climate change and water use change can interact in modifying ET (and R). With maintained irrigation practices, R is likely to decrease to near-total depletion, with risk for cascading ecological regime shifts in aquatic ecosystems downstream of irrigated land areas. Without irrigation, the agricultural areas of the principal Syr Darya river basin could sustain a 50% higher T increase (of 2.3 °C instead of the projected 1.5 °C until 2010–2039) before yielding the same consumptive ET increase and associated R decrease as with the present irrigation practices.

Assessment of the Draft Hydrological Basin Plan of the Guadalquivir River Basin (Spain)

This paper evaluates and discusses the draft Hydrological Basin Plan (HBP) for the Guadalquivir river basin and its related Programme of Measures (PoM). The HBP focuses on demand management using technical and economic measures, particularly through investment in water efficiency measures. In addition, it seeks to eliminate urban point source pollution. By 2015, a sustainable water resource demand is projected if the current area of irrigated land is not expanded and if the urban waste water treatment work is completed according to Directive 91/271/CEE. It is expected that costs of implementation will be high. The total investment of the PoM is estimated to be €978 per capita per year; this investment has an annual equivalent cost of €143 per capita per year. However, it is estimated that 67% of the total investment can be recovered with special impact in increase in the cost of irrigation water by 160% and the cost of urban water by 60%. Finally, this paper ends with a discussion on the most critical points likely to hinder the HBP being used effectively as a tool for sustainable water management.

Determinants of household food access among small farmers in the Andes: examining the path.

Household food access remains a concern among primarily agricultural households in lower- and middle-income countries. We examined the associations among domains representing livelihood assets (human capital, social capital, natural capital, physical capital and financial capital) and household food access. Cross-sectional survey (two questionnaires) on livelihood assets. Metropolitan Pillaro, Ecuador; Cochabamba, Bolivia; and Huancayo, Peru. Households (n = 570) involved in small-scale agricultural production in 2008. Food access, defined as the number of months of adequate food provisioning in the previous year, was relatively good; 41 % of the respondents indicated to have had no difficulty in obtaining food for their household in the past year. Using bivariate analysis, key livelihood assets indicators associated with better household food access were identified as: age of household survey respondent (P = 0.05), participation in agricultural associations (P = 0.09), church membership (P = 0.08), area of irrigated land (P = 0.08), housing material (P = 0.06), space within the household residence (P = 0.02) and satisfaction with health status (P = 0.02). In path models both direct and indirect effects were observed, underscoring the complexity of the relationships between livelihood assets and household food access. Paths significantly associated with better household food access included: better housing conditions (P = 0.01), more space within the household residence (P = 0.001) and greater satisfaction with health status (P = 0.001). Multiple factors were associated with household food access in these peri-urban agricultural households. Food security intervention programmes focusing on food access need to deal with both agricultural factors and determinants of health to bolster household food security in challenging lower- and middle-income country contexts.

On the relationship between historical land‐use change and water availability: the case of the lower Tarim River region in northwestern China

AbstractNatural ecosystems in the region of the lower Tarim River in northwestern China strongly deteriorated since the 1950s due to an expanding desertification. As a result, the downstream Tarim River reaches became permanently dry land. This historical evolution in land‐use change is typically the result of the anthropogenic impact on natural ecosystems. On the basis of a spatially distributed hydrological catchment model bidirectionally linked with a fully hydrodynamic MIKE11 river model, land‐use changes characterized by historical changes in leaf area index (LAI) of vegetation, as well as the evolution of irrigated surface areas, can be causally related to changes in water resources (groundwater storage and surface water resources). An increased surface area of irrigated (agricultural) land, together with a majority of inefficient irrigation methods, did lead to a strong increase of water resources consumption of the farmlands located in the upper Tarim River area. Evidently, this evolution influenced available water resources downstream in the Tarim basin. As a result, farmland has been gradually relocated to the upstream regions. This has led to reduced flows from the upper Tarim stream, which subsequently accelerated the dropping of the groundwater level downstream in the basin. This study moreover demonstrates that land surface biomass changes (cumulative LAI) along the lower Tarim River are strongly related to the changes in groundwater storage. Copyright © 2012 John Wiley & Sons, Ltd.

Vapor flux by evapotranspiration: Effects of changes in climate, land use, and water use

Enhanced evapotranspiration (ET) over irrigated land and associated latent heat flux change can modify the climate. Model studies of such climate change effects of irrigation are commonly based on land use parameterizations, in terms of irrigated land area, or land area equipped for irrigation. Actual ET change, however, may also be driven by water use change in addition to land use change. This study quantifies and compares ET changes due to changes in climate, land use, and water use from the preirrigation period 1901–1955 to the recent period 1990–2000 (with irrigation) for the example case of Mahanadi River Basin (MRB) in India. The results show that actual water use per unit area of irrigated land may vary greatly over a hydrological drainage basin. In MRB, much higher water use per irrigated land unit in the downstream humid basin parts leads to higher vapor flux by ET, and irrigation‐induced ET flux change, than in the upstream, water‐stressed basin parts. This is consistent with water supply limitations in water‐stressed basins. In contrast, the assumption in land use−based models that irrigation maintains high soil moisture contents can imply higher modeled water use and therefore also higher modeled ET fluxes under dry conditions than under humid conditions. The present results indicate water use as an important driver of regional climate change, in addition to land use and greenhouse gas‐driven changes.

Development of a Muskingum- Cunge routing model for design of furrow irrigation

Surface irrigation projects which accounts for almost all of the irrigated land areas of the world has been studied extensively by many investigators and their performance was found to be lower than expected. Many of these projects are built and operated without adequate technical input, with consequent low uniformity and efficiency of water application. However, irrigators are still faced with significant challenges in making both design and operation of surface irrigation systems more efficient. In this study a mathematical design approach for furrow irrigation was developed as spreadsheet model to simulate all hydraulic phases of water movement as aid to design and to evaluate the performance of furrow irrigation. The irrigation model simulates the hydraulics of furrow irrigation at the field scale. The principle role of the model is the evaluation of alternative field layouts (field length and slope) and management practices (water application rates and cut-off times). Input data requirements for the simulation component include field length, slope, infiltration characteristics (or advance data), target application depth, water application rate, Manning’s resistance and furrow geometry. A series of simple relations were presented for estimating the advance, recession, and performance of surface irrigation systems. The approach uses continuity to compute the advance time to field end and half the distance to field end. The irrigation methods differ slightly in how the surface volume is computed. Initially a surface shape factor is used to compute storage volume during advance phase; however, estimation of this storage volume was corrected during storage, depletion and recession phases by utilizing Muskingum-Cunge routing method. The subsurface volume calculations use a modified Kostiakov equation that includes both an initial sink term and a constant final infiltration rate. Recession calculations differ for each method. With sloping methods, adjustments to a straight line recession curve make recession estimates more reasonable. It is shown that the procedure can produce reasonable predictions of design performance over a range of conditions. Model verification was made by its comparison with FAO-surface-model, and zero-inertia model using data from furrow fields of Kenana Sugar Scheme-Sudan.

Estimation of irrigation requirement for sustainable water resources reallocation in North China

The South�North Water Transfer (SNWT) project (upon completion) will deliver some 4.8 billion m3 of water per annum to Hebei, Beijing and Tianjin � greatly mitigating water shortage in North China. Surface water that is currently restricted to urban use could then become partly available for agricultural production. This will reduce the dependence of agriculture on groundwater, which will in turn retard groundwater depletion in the region. This study determines the spatial and temporal distributions of agricultural water requirement in Hebei Plain. This in turn lays the basis for surface water reallocation following the completion of the SNWT project. DSSAT and COTTON2K crop models are used along with crop coefficient methods to estimate required irrigation amounts for wheat, maize, cotton, vegetables and fruit trees in Hebei Plain. The study uses 20 years (1986�2006) of agronomic, hydrologic and climate data collected from 43 well-distributed stations across the plain. Based on the results, wheat accounts for over 40% of total irrigation water requirement in the plain. Similarly, wheat, maize and cotton together account for 64% of the total irrigation water requirement. The piedmont regions of Mount Taihang have the highest irrigation requirement due to high percent farm and irrigated land area. The months of April and May have the highest irrigation water requirement, respectively accounting for 18.1% and 25.4% of average annual irrigation. Spatial and temporal variations in our estimated irrigation water requirement are higher than those in the officially published statistics data. The higher variations in our results are more reflective of field conditions (e.g. precipitation, cropping pattern, irrigated land area, etc.). This therefore indicates a substantive improvement (in our study) over the average statistical data. Based on our simulation results, viable surface water reallocation strategies following the completion of the SNWT project are advanced and discussed.

Farm-level perspectives regarding irrigation water prices in the Tulkarm district, Palestine

Agriculture consumes about 70% of water available in the Occupied Palestinian Territories. Domestic and industrial users utilize 30% of the water supply. Water resource managers are considering the policy of reallocating a portion of the water supply from agriculture to other uses. It is believed that increasing irrigation water prices could influence water consumption and thus make water available for non-agricultural (more economic) uses. This paper examines the impacts of water pricing on agricultural water consumption and farming profitability and provides some guidelines for policy makers regarding water pricing as a tool to manage scarce water resources. We estimate a regression model describing agricultural water consumption as a function of water prices, irrigated land area, farm income, and irrigation frequency, using data collected in a survey of about 150 farmers in the Tulkarm district. We conclude that irrigation water prices are perceived as high and comprise a large portion of total farming expenses. Therefore, attempts to increase irrigation water prices in the Tulkarm district might jeopardize farming feasibility and might have substantial impacts on agricultural water consumption. Nevertheless, many farmers would continue farming even if the water prices were increased beyond their willingness to pay threshold.

Response of the hydrological regime of the Yellow River to the changing monsoon intensity and human activity

In the past 50 years, influenced by global climate change, the East Asian summer monsoon intensity (SMI) changed significantly, leading to a response by the water cycle of the Yellow River basin. The variation in SMI has three stages: (1) 1951–1963, SMI increased; (2) 1963–1965, SMI declined sharply, a feature that may be regarded as an abrupt change; and (3) 1965–2000, SMI remained at low levels and showed a tendency to decline slowly. The decreased SMI led to a reduction in water vapour transfer from the ocean to the Yellow River basin, and thus precipitation decreased and the natural river runoff of the Yellow River also decreased. Due to the increase in population and therefore in irrigated land area, the ratio of net water diversion to natural river runoff increased continuously. Comparison of the ratio of net water diversion to natural river runoff before and after the abrupt change in SMI indicates some discontinuity in the response of the man-induced lateral branch of the water cycle to the abrupt change in SMI. The frequently occurring flow desiccation in the lower Yellow River can be regarded as a response of the water cycle system to the decreasing summer monsoon intensity and increasing population. When the ratio of net water diversion exceeded the ratio of natural runoff of the low-flow season to the annual total natural runoff, flow desiccation in the lower Yellow River would occur. When the ratio of net water diversion is 0.3 larger than the ratio of the natural runoff of the low-flow season to the annual total natural runoff, an abrupt increase in the number of flow desiccation events is likely to occur.

Irrigation in the Texas High Plains: a brief history and potential reductions in demand

AbstractIrrigation for crop production in the semi‐arid Texas High Plains is dependent on groundwater withdrawals from the Ogallala Aquifer, which is declining because withdrawals exceed natural recharge. Irrigation development in the region accelerated during the 1950s. Both irrigated area and volume pumped peaked in 1974 and steadily declined during 1974–1989. By 2004, however, irrigated area was nearly the same as it was in 1958, and volume pumped had increased slightly. Several strategies to reduce groundwater withdrawals were reviewed without any reductions in irrigated land area or crop productivity. The most promising evaluated were: (1) increasing weather‐based irrigation scheduling using the Texas High Plains Evapotranspiration Network (TXHPET); (2) converting gravity‐irrigated land (27% of total) to centre pivot irrigation; and (3) replacing high‐water to lower‐water demand crops (i.e., corn to cotton). If the land area using the TXHPET network was doubled, and if gravity‐irrigated lands were reduced to 10%, groundwater withdrawals could be reduced by 14%. An additional reduction of 8% may be possible by converting half of the irrigated corn area to cotton. Copyright © 2008 John Wiley & Sons, Ltd.

Megaprojects and Social and Environmental Changes: The Case of the Thai “Water Grid”

Large-scale development of irrigation has long been an attractive option of postwar development, and the Mekong region has been no exception. Thailand has developed approximately four million hectares of irrigated land, and its northeastern region (Isaan)--both the driest and poorest part of the country--has been the target of many water projects. However, "full development" of its potential has been constrained by the lack of storage sites and the difficulty of diverting water from the Mekong River. Several ambitious projects have been discussed during the last 50 y, all of which have been aimed at "greening Isaan." In 2003, the Thai administration launched the idea of a national "water grid" that would triple the area of irrigated land in the country. This paper analyzes the emergence of this megaproject, its governance, and its economic and environmental soundness.

Breeding for abiotic stresses for sustainable agriculture.

Using cereal crops as examples, we review the breeding for tolerance to the abiotic stresses of low nitrogen, drought, salinity and aluminium toxicity. All are already important abiotic stress factors that cause large and widespread yield reductions. Drought will increase in importance with climate change, the area of irrigated land that is salinized continues to increase, and the cost of inorganic N is set to rise. There is good potential for directly breeding for adaptation to low N while retaining an ability to respond to high N conditions. Breeding for drought and salinity tolerance have proven to be difficult, and the complex mechanisms of tolerance are reviewed. Marker-assisted selection for component traits of drought in rice and pearl millet and salinity tolerance in wheat has produced some positive results and the pyramiding of stable quantitative trait locuses controlling component traits may provide a solution. New genomic technologies promise to make progress for breeding tolerance to these two stresses through a more fundamental understanding of underlying processes and identification of the genes responsible. In wheat, there is a great potential of breeding genetic resistance for salinity and aluminium tolerance through the contributions of wild relatives.

Soil–water and solute movement under precision irrigation: knowledge gaps for managing sustainable root zones

Precision irrigation involves the accurate and precise application of water to meet the specific requirements of individual plants or management units and minimize adverse environmental impact. Under precision irrigation applications, water and associated solute movement will vary spatially within the root zone and excess water application will not necessarily result in deep drainage and leaching of salt below the root zone. This paper estimates that 10% of the irrigated land area (producing as much as 40% of the total annual revenue from irrigated land) could be adversely affected by root zone salinity resulting from the adoption of precision irrigation within Australia. The cost of increases in root zone salinisation due to inappropriate irrigation management in the Murray and Murrumbidgee irrigation areas was estimated at AUD 245 million (in 2000/01) or 13.5% of the revenue from these cropping systems. A review of soil–water and solute movement under precision irrigation systems highlights the gaps in current knowledge including the mismatch between the data required by complex, process-based soil–water or solute simulation models and the data that is easily available from soil survey and routine soil analyses. Other major knowledge gaps identified include: (a) effect of root distribution, surface evaporation and plant transpiration on soil wetted patterns, (b) accuracy and adequacy of using simple mean values of root zone soil salinity levels to estimate the effect of salt on the plant, (c) fate of solutes during a single irrigation and during multiple irrigation cycles, and (d) effect of soil heterogeneity on the distribution of water and solutes in relation to placement of water. Opportunities for research investment are identified across a broad range of areas including: (a) requirements for soil characterisation, (b) irrigation management effects, (c) agronomic responses to variable water and salt distributions in the root zone, (d) potential to scale or evaluate impacts at various scales, (e) requirements for simplified soil–water and solute modelling tools, and (f) the need to build skills and capacity in soil–water and solute modelling.

Trace element concentrations in soils under different land uses in Mpumalanga Province, South Africa

Trace element deficiencies and toxicities have become important aspects of land quality and are affected by the increased pressure on land from industrialisation and agricultural practices. The objective of the study was to determine if differences occur in trace element concentrations in soils under different land uses in the Mpumalanga province of South Africa. Land uses were divided into four groups, namely rangeland, irrigation, dryland, and resource-poor. Two extraction methods were used, i.e. ammonium-EDTA and EPA 3050 acid digestion. The extracted solutions were analysed using an Inductively Coupled Plasma-Mass Spectrometer (ICP-MS) or Atomic Adsorption Spectrophotometry (AAS). The trace element concentrations followed the trend: irrigated > > dryland > rangeland resource-poor for B, As, Co, Cr, Cu, I, Mn, Ni and Zn, with few exceptions. There appeared to be additions of trace elements to irrigated land and dryland areas, and depletion from resource-poor farm lands. Trace elements that were exceeded suggested threshold concentrations and/or were raised in irrigated lands are B, As, Co, Cu, Hg, Mn, Ni, Se, V and Zn. Trace elements that were lower than suggested deficiency threshold, especially for the resource-poor farm lands, are B, Co, Cr, Cu, Fe, I, Mn, Mo, Se and Zn.

Direct human influence of irrigation on atmospheric water vapour and climate

Human activity increases the atmospheric water vapour content in an indirect way through climate feedbacks. We conclude here that human activity also has a direct influence on the water vapour concentration through irrigation. In idealised simulations we estimate a global mean radiative forcing in the range of 0.03 to +0.1 Wm–2 due to the increase in water vapour from irrigation. However, because the water cycle is embodied in the climate system, irrigation has a more complex influence on climate. We also simulate a change in the temperature vertical profile and a large surface cooling of up to 0.8 K over irrigated land areas. This is of opposite sign than expected from the radiative forcing alone, and this questions the applicability of the radiative forcing concept for such a climatic perturbation. Further, this study shows stronger links than previously recognised between climate change and freshwater scarcity which are environmental issues of paramount importance for the twenty first century.

Water efficiency of agricultural production in China: regional comparison from 1999 to 2002

We apply stochastic frontier analysis (SFA) techniques to a provincial level data set to measure technical and water efficiency in China's agricultural production from 1999 to 2002. The determinants of the efficiencies are identified together with the physical determinant structure of the irrigation factor, which refers to the water use per irrigated land area. The study yields the following three main results: corn is the most important crop in improving economic and water efficiency; the mean annual temperature is highly elastic to the change in water efficiency; water reservoirs facilitate the utilisation of irrigation water but could lead to less efficiency in water use.

Impact of Atmospheric Correction on Land-use Classification and Water Demand for the Aral Sea Basin

The Aral Sea, once the fourth largest inland sea in surface area in the world, is located at the border between Kazakhstan and Uzbekistan. Water was taken out from two major rivers to expand the area of irrigated land, resulting in desertification of the sea. The drying part of the sea remained heavily salted after water evaporation, causing salt and dust storms and therefore Aeolian deposition of these components on plants, affecting agricultural productivity and quality. Atmospheric effects in the interpretation of time series images of land characteristics are used to estimate currently cultivated areas being irrigated in the Syrdarya flood plain, to determine water demand. This paper examines differences between single and time series land classification, and the effects of atmospheric correction. Ground-truth data from a fieldtrip in Kazakhstan are presented.

Tropical wheat response to irrigation and nitrogen in a Sahelian environment. I. Grain yield, yield components and water use efficiency

Every year, increasing areas of irrigated land are being planted to tropical wheat ( Triticum aestivum L.) in the Sahel. However, knowledge on how irrigation and nitrogen (N) supply can be simultaneously manipulated to realize maximum yield potential is limited. A 2 year field study was conducted to determine wheat response to differential seasonal irrigation regimes ranging from 300 to 690 mm applied water and 5 N levels of 0 40, 80, 120 and 160 kg N ha −1. Grain yield and all primary yield components increased linearly in response to irrigation in both seasons. Water use generally increased linearly with increased seasonal irrigation and applied N. A quadratic response in grain yield and kernel number m −2 was observed with increasing N levels in all irrigation regimes both seasons. Grain yield, spikes m −2, kernels spike −1, number of kernels m −2 and kernel weight responses to irrigation were greater at the higher N rates. Spikes m −2 were reduced with water deficit. In both years, the average reduction in number of kernels m −2 at the maximum irrigation deficit was 40.6 and 45% at 0 and 160 kg N ha −1, respectively. Similar reduction occurred in kernels −1 spike, where water deficit decreased this component an average of 21.4 and 31.8% at the lowest and highest N rates, respectively. Water deficit over both years reduced kernel weight by 12 and 19.4% at the lowest and highest N rates. This study showed that optimizing irrigation and N supply in a Sahelian environment can produce economic grain yield, and maximize economic return from wheat production. Nitrogen rate must be matched with the irrigation water available to increase water use efficiency and maximize profits.