Agricultural Groundwater Use Research Articles

Agricultural groundwater use and rural livelihoods in sub-Saharan Africa: A first-cut assessment

The rapid expansion in agricultural groundwater use in the last few decades has transformed rural economies in large parts of the developing world, in particular South Asia and North China. There has been no such “Groundwater Revolution” in most of sub-Saharan Africa and little is known about the actual role of groundwater use in supporting agricultural livelihoods in the region or opportunities to expand this role in the future. Published literature has been reviewed to paint a preliminary, region-wide picture of the contribution groundwater makes to agriculture, and in turn to rural livelihoods, within sub-Saharan Africa. The findings indicate that groundwater is used on only 1–2 million hectares of cropped area, directly contributing to the livelihoods of 1.5–3% of the rural population. Groundwater also plays a critical role in the vital livestock sector as well as an important indirect role in the supply of domestic water to agricultural households. While data are lacking, these latter two roles likely surpass the direct importance of groundwater to crop production. This suggests that an understanding of the value of agricultural groundwater use in support of rural livelihoods in sub-Saharan Africa should be based on different models than have typically been applied in Asia.

Production of Perennial Vegetation in an Oasis-desert Transition Zone in NW China - Allometric Estimation, and Assessment of Flooding and Use Effects

River oases at the southern fringe of the Taklamakan desert in NW China are surrounded by belts of spontaneous vegetation that protect the oases from sand drift. As an important source of forage, fuel and construction wood, this foreland vegetation is also a component part of the agricultural system of the oases but has been, and still is, destroyed through overuse. Within a broader study that aimed to provide a basis for a sustainable management of this foreland vegetation, biomass and production were studied in four vegetation types dominated either by Alhagi sparsifolia, Calligonum caput-medusae, Populus euphratica, or Tamarix ramosissima that were thought to occur under different regimes of natural flooding in the foreland of Qira (Cele) oasis, Xinjiang, NW China. Shoot biomass components were closely correlated to basal area (Calligonum, Populus, Tamarix) or shrub volume and projection area (Alhagi), enabling non-destructive estimation of stand biomass from shoot diameters or shrub dimensions with sufficient precision using allometric regression equations. Relationships between shoot basal area and biomass of the woody species (Calligonum, Populus and Tamarix) agreed with predictions by a theoretical model of plant vascular systems, suggesting that they are determined by hydraulic and mechanical requirements for shoot architecture. Average aboveground biomass densities of typical stands in late summer were 2.97 Mg/ha in Alhagi, 3.6 Mg/ha in a row plantation and 10.9 Mg/ha in homogenous stands of Calligonum, 22–29 Mg/ha in 22 year-old Populus forests and 1.9–3.1 Mg/ha in Tamarix-dominated vegetation. Annual aboveground production including wood and assimilation organs ranged from 2.11 to 11.3 Mg/ha in plantations of Calligonum, 3.17 to 6.12 Mg/ha in Populus, and 1.55 to 1.74 Mg/ha (based on total ground area) or 3.10 to 7.15 Mg/ha (in homogenous stands) in Tamarix. Production of Alhagi is equal to peak biomass. A thinning treatment simulating use by the local population enhanced productivity of Calligonum, Populus and Tamarix. A complete harvest of Alhagi in late August decreased production in the following year. An artificial flood irrigation treatment did not sufficiently increase soil water content except in the uppermost layer and had no clear beneficial effect on growth of the four species and even a negative effect on Alhagi, which was due to increased competition from annual species. As biomass and production with or without artificial irrigation were much higher than values expected for rain-fed desert vegetation at a mean annual precipitation of 35 mm, it is concluded that the existence of all vegetation types studied is probably based on permanent access to groundwater and that natural floods or precipitation do not contribute to their water supply. The effects of agricultural groundwater use in the oasis on groundwater in the foreland of the oasis need further study. Sustainable use of this productive vegetation is possible but requires proper management.

River Regime Changes in the Upper Part of Khabour Catchment Area in North-Eastern Syria in the Second Half of the XXth Century – part I: Annual Runoff

The papers deals with hidrography ofthe Upper Jazirah region in north-eastern Syria, particularly with the changes in the mean and annual runoff of the Khabour River and its tributaries in 1943-2001 period. The upper partof the Khabour catchment area is an important Syrian cotton and wheat production area. The use of ground-water and river-water in agriculture, especially since 1970's lead to significant lowering of the annual runoff of the Khabour and other rivers in the area.

Economic value of groundwater: case studies from four villages in Banaskantha, north Gujarat

Though groundwater markets exist widely in north Gujarat and the selling price is often considerably high, reflecting the scarcity value of the resource, the question often asked by policy-makers is whether the scarcity value is realized under the existing uses such as irrigation and milk production. This is because farmers who own tube wells and enjoy unlimited access to the resource, are not fully confronted with the opportunity cost of using water due to heavily subsidized electricity, and divert the water for growing crops that are economically inefficient. A study carried out in four villages in Gujarat’s Banaskantha district estimated the marginal value product of groundwater use to be 32.4 million rupees. A major share (60%) of the net farm output generated through groundwater use in agriculture came from dairying.

Book reviews

Book reviewed in this article: Management of Shared Groundwater Resources: The Israeli‐Palestinian Case with an International Perspective Eran Feitelson and Marwan Haddad (Eds.) Rural planning and management Joe Morris, Alison Bailey, R. Kerry Turner and Ian J. Bateman (Eds.) Rural Financial Markets in Asia: Policies, Paradigms, and Performance (Study of Rural Asia, Vol. 3) Richard Meyer and Geetha Nagarajan (Authors) The Biotechnology Revolution in Global Agriculture: Invention, Innovation and Investments in the Canola Sector Peter W.B. Phillips, George G. Khachatourian (Eds.) Agricultural Use of Groundwater: Towards Integration Between Agricultural Policy and Water Resources Management Cesare Dosi (Ed.)

Sustaining Asia’s groundwater boom: An overview of issues and evidence

This article suggests that Asia’s groundwater socio‐ecology is at an impasse. Rapid growth in groundwater irrigation in South Asia and the North China plains during the period 1970–95 has been the main driver of the agrarian boom in these regions. India, Pakistan, Bangladesh and China account for the bulk of the world’s use of groundwater in agriculture. On the plus side, groundwater development has provided sustenance to agrarian economies and millions of rural livelihoods. On the downside, it has created chronic problems of resource depletion and quality deterioration. While problems of groundwater depletion, pollution and quality deterioration are indeed serious, so are the consequences of the degradation of the resource for those that have come to precariously depend upon groundwater irrigation.Three problems currently afflict groundwater use: depletion due to overdraft; water logging and salinization; and pollution due to agricultural, industrial and other human activity. The pathology of the decline in groundwater socio‐ecology reflects a remarkably similar pattern across regions. The critical issue for Asia now is: what might be done to sustain and revive these groundwater socio‐ecologies vital to the region’s economy? This article reviews a variety of techno‐institutional approaches. However, transposing lessons from the industrialized world uncritically in the Asian context may not work. A more nuanced understanding of the peculiarities of Asia’s groundwater socio‐ecology is needed.

「平成6年(1994年)列島渇水」における農業用の地下水利用と障害

「平成6年(1994年)列島渇水」における農業用の地下水利用と障害

Methane in groundwater used for Japanese agriculture: Its relationship to other physico‐chemical properties and possible tropospheric source strength

The concentration of CH4 in 131 groundwater samples used for agriculture in Aichi Prefecture, central Japan, averaged 1.58 mgC l−1 for those water samples above detection (>0.006 mgC l−1), with the highest value of 18.4 mgC l−1. Methane was detected in more than half of the groundwater samples. The amount of CH4 released to the atmosphere because of agricultural groundwater use was estimated to be 2.00 × 107 gC yr−1 for a cultivated area of 8.61 × 104 ha, or about 1.4% of the CH4 production in paddy fields derived from soil organic matter in the same geographic area. Distribution of measurements of redox potential (Eh), chemical oxygen demand (COD), Fe, Mn, NH4‐N, and NO3‐N was clearly different between the CH4‐detected and undetected samples; Eh values and NO3‐N concentrations were lower while the other four factors were higher in the CH4‐detected samples.

Local Aquifer Recharge to Stabilize Spring Discharges

The June 1989 article by Echelle, Echelle, and Edds, Conservation genetics of a spring-dwelling desert fish, the Pecos gambusia, (Gambusia nobilis, Poeciliidae) states that the overdrafting of ground water in their study area has been responsible for drying up springs in the past and threatens to dry up more springs in the future. These springs are habitats of the Pecos gambusia, as well as other endemic fish and invertebrates. The authors stated that agricultural use of ground water is a major reason for the lowering of the water table in many of their study areas. One alternative to prevent the lowering of the water table is to regulate pumping rates. However, regulation of pumping rates is very difficult because agriculture in the West is dependent on huge withdrawals of ground water. Even if a desert area is taken out of agriculture there are other threats to ground water supplies, e.g., the growth and sprawl of western cities (Swanson 1989). Another option to prevent the drying of springs is to recharge the aquifer to stabilize or raise the local water table. Pumping and recharge wells have been successfully used in hydrogeology to divert or contain contaminant plumes in ground water (Moz & Bell 1977; Atwood & Gorelick 1985; Aral 1989). However, this author is not aware of any attempts to modify the water table to protect a biotic community dependent on ground water discharges. Figure 1 is a schematic view of a simplified aquifer. The large withdrawals caused by agricultural, residential, and industrial use create a cone of depression that changes ground water flow and lowers the water table. Eventually, the spring presented in the diagram will dry

Algorithm for Surface/Ground‐Water Allocation under Appropriation Doctrine

ABSTRACTA stream‐aquifer simulation model was developed to evaluate different conjunctive use management strategies in the South Platte River in Colorado. A component of this model simulates the allocation of surface and ground water for agricultural use. The water law based on the doctrine of prior appropriation provides the basic framework for water allocation in the study area. The physical sequence in which the river diversions are located along the river is different from the sequence in which the water has to be allocated according to the priority of rights. An algorithm is designed to allocate the river flows computed by the physical simulation component of the model to the appropriators according to the water rights and other imposed criteria as specified by the conjunctive management scheme under study. The algorithm is demonstrated on a management problem involving the evaluation of a streamflow augmentation scheme in the study reach.

Water Quality and Regional Water Supply Planning

A method for sizing a flow‐way to remove phosphorus from surplus rainfall runoff is presented. The flow‐way area would consist of a seasonal wetland community wherein the plants take up the nutrient. The paper presents the integration of scientific water quality study results with engineering surface water quantity procedures. Benefits of the plan include: (1) Use of surface water reduces agricultural use of groundwater; (2) use of surplus runoff reduces use of existing surface water resources; (3) use of a flow‐way maintains regional water quality; and (4) use and management of existing surface water provides economic benefits.

Conjunctive use of groundwater and surface water for irrigated agriculture: Risk aversion

In examining the South Platte system in Colorado where surface water and groundwater are used conjunctively for irrigation, we find the actual installed well capacity is approximately sufficient to irrigate the entire area. This would appear to be an overinvestment in well capacity. In this paper we examine to what extent groundwater is being developed as insurance against periods of low streamflow. Using a simulation model which couples the hydrology of a conjunctive stream aquifer system to a behavioral‐economic model which incorporates farmer behavior in such a system, we have investigated the economics of an area patterned after a reach of the South Platte Valley in Colorado. The results suggest that under current economic conditions the most reasonable groundwater pumping capacity is a total capacity capable of irrigating the available acreage with groundwater. Installing sufficient well capacity to irrigate all available acreage has two benefits: (1) this capacity maximizes the expected net benefits and (2) this capacity also minimizes the variation in annual income: it reduces the variance to essentially zero. As pumping capacity is installed in a conjunctive use system, the value of flow forecasts is diminished. Poor forecasts are compensated for by pumping groundwater.