Rainwater harvesting in arid and semi-arid zones

In arid and semi-arid regions, the scarcity of water can be alleviated by rainwater harvesting, which is defined as a method of inducing, collecting, storing, and conserving local surface runoff for agriculture. Rainwater harvesting can be applied with different systems, and this dissertation deals with the system of micro-catchments. A microcatchment consists of a runoff area and a basin area in which a tree is planted. The purpose of this study was to develop a design procedure for micro-catchments, applicable to environmental and human conditions prevailing in developing countries. Underlying the design procedure is an analysis of the water balance of the system.The design method is based on a prediction of actual transpiration by the numerical soil-water-balance model SWATRE, while the runoff component is predicted by a runoff model. The design- aims at sufficient soil water being available in an average rainfall year. Deep percolation losses occur in wet years, and water shortages in dry years. A tree suitable for these conditions is able to withstand dry periods and drought years. The practical problem selected for this study was the establishment of Neem windbreaks in Niger and Nigeria. Points to consider in the design are the seasonal distribution of rainfall, the soil hydraulic conditions, and the tree hydrological/ physiological characteristics.The theory of four surface runoff models is presented. These models are compared in their capability and accuracy to predict runoff volumes for micro-catchment design and in their model concept, structure, parameters, and input data requirement. A kinematic-wave model with depression storage and a linear regression model are considered the most suitable for micro-catchment design. The theory of the soil-water-balance model is discussed, as is the calibration of this model with data from Sede Boqer in the Negev Desert. The application of the model for micro-catchment design is demonstrated for an extremely and zone and an and zone in the Negev Desert.The extremely and zone is too dry for rainwater harvesting from micro-catchments, larger catchments being required there. In the and zone, the basin areas should be approximately 40 m 2for each tree, and the runoff areas 60 m 2. The design approach is applied to five weather stations in Niger and northern Nigeria where data were available. Data from a Neem windbreak at Sadoré in Niger were used to calibrate the model. Data from Niamey, near Sadoré, were used to compare runoff prediction with two runoff models and to predict micro-catchment design. The combination of a runoff-depth model and the soil-water-balance model was used to predict microcatchment design at Sadoré, and Tahoua in Niger and at Sokoto and Katsina in Nigeria.The conclusion of the design predictions is that the required runoff area per tree is about 40 m 2at Tahoua and about 20 m 2at Niamey, Sadoré, Sokoto, and Katsina. With such runoff areas, a good growth of trees could be achieved at degrees varying roughly from 40% of a certain target transpiration at Niamey, 50% at Sadoré, 80% at Sokoto, and 100% at Katsina. The overall conclusion is that, in and and semi-arid zones, runoff from small areas such as micro-catchments is an important potential source of water for the establishment, development, and growth of trees. A supply of runoff water can make the difference between death, survival, minimum development, and good growth of trees. Especially in dry years, the runoff water can considerably improve the environmental conditions in which the trees have to grow.The data required to apply this approach and arrive at a preliminary design are discussed. Rainfall and evaporation records are needed to supply important weather data. Data on topography, soil profile, soil hydraulic functions, and tree hydrological characteristics can be measured or estimated in the field, or determined in a laboratory from samples. With a preliminary design, well-conceived field experiments can be set up. As more data become available from the field, the design can be adjusted and worked out in detail for a particular location.The only potential alternative method of water supply to a windbreak would be trickle irrigation. But this would enhance the development of a shallow root system and would require a source of water, high capital investment, and irrigation management skills. All these requirements are difficult to realize for a windbreak. Instead, for this application, rainwater harvesting from micro-catchments is suitable, cheap, good, and efficient. Rainwater harvesting should be seen as complementing irrigated agriculture, rather than competing with it. Irrigated agriculture is practised on the best soils, where water is available to grow field crops. Rainwater harvesting is a good alternative on marginal lands where irrigation water is not available. Because of dry periods and drought years, rainwater harvesting works best for deep-rooting, drought-resistant trees.The technology involved is not complicated and can easily be adapted to local conditions of climate, soil, and trees. In many of these areas, there is a lack of water, wood, food, and shade, while wind erosion is a major problem. Windbreaks and shelterbelts can serve both the local population and the environment. Once the trees have been planted and the runoff areas constructed, some annual maintenance is needed but no continuous care. This is important for nomads, who are not farmers. Windbreaks demarcate and protect farmland, while large-scale shelterbelts consisting of different types of trees and bushes also serve nomads who do not settle. Microcatchments also reduce soil erosion by water, because they control surface flow. In addition, deep percolation in wet years recharges the groundwater. This can help to redress an upset regional water balance and combat desertification

Reuse of drainage water for rice and wheat growth during reclamation of saline-sodic soils in Pakistan under the national drainage program (NDP)

Pakistan is facing scarcity of canal water for irrigated agriculture on 16 mha land. This problem is caused, among others, by the loss of surface storage capacity and by the current prolonged dry spell lasting over the several past years. Siltation of Mangla, Tarbela and Chashma Dams have caused a loss of . 5 km3 which is 25 % of the design capacity. Since this problem is increasing, there may be a gradual decrease of food production for a population of 140 million, which is expected to have doubled by 2025. Water shortage is the most serious for the provinces of Punjab and Sindh, where ground water is of hazardous quality and about 75 % of pumped ground water is not safe for irrigation without amendments. In this scenario, it appears wise and timely to study the prospects of growing food grains during reclamation of salt-affected soils using ground water to save good quality canal water for irrigating good soils. Under arid and semi-arid conditions of Pakistan with scarce and irregular rainfall, limited leaching of salts promotes soil salination followed by sodication, induced by irrigation with ground water of high EC, SAR and RSC without amendments or other agronomic management practices. In this way, 6 mha of soils have become salt-affected, of which 60 % are saline-sodic and needs a source of calcium for amelioration. For initial reclamation of salt-affected soils, low quality irrigation waters are generally useful and some times even better than canal water, due to favorable effects of electrolytes on infiltration rate and hydraulic conductivity. For a variety of reasons, farmers are not properly applying the technologies for reclamation and management of saline-sodic soils. To improve this situation on sustainable basis, Univ. Agri., Faisalabad has launched a three-year research study on reclamation of saline-sodic soils by reusing drainage water, in which farmers are participating. The experiments were started in June 2001 in the Fourth Drainage Project Area located in the Central Punjab and are funded by the National Drainage Programme. The reclamation technologies include split application of gypsum @ soil or water GR alone and in combination with FYM or green manure, and on-farm wheat seed priming. This paper will present preliminary results and recommendations pertaining to economical as well as sustainable reuse of drainage water on saline-sodic soils, farmers' constraints and limitations for adapting the required technologies in this regard on the basis of the on-going experiments

Comparison of sulfurous acid generator and alternate amendments to improve the quality of saline-sodic water for sustainable rice yields

The prolonged irrigation with marginal quality water can cause secondary salinization of soils, which necessitates for better understanding of water management alternatives. Relative performance of sulfuric acid and gypsum is still controversial to counter sodium hazards in soil/water system. As an alternative, sulfurous acid generators (SAG) are also being marketed. But up-till-now, there is not even a single field study published in scientific journals about their efficiency and economical viability for the treatment of saline-sodic water. Therefore, a field study was carried out to compare the effectiveness of SAG and alternate amendments applied on an equivalent basis to grow rice crop. SAG treatment of saline-sodic tube well water decreased only residual sodium carbonate (RSC) from 5.4 to 3.6 mmolc l¿1, and had no beneficial effect on its sodium adsorption ratio (SAR) or electrical conductivity (EC). All the treatments kept soil EC and SAR around their respective threshold levels. For paddy yield, SAG, sulfuric acid, and gypsum treatments depicted nonsignificant differences. SAG and sulfuric acid treatments of water were about six times expensive than that of gypsum. It was concluded that soil-applied gypsum, to counter sodic hazards of irrigation water, is economical to sustain irrigated rice in dry regions

Strategies for productive use of brackish water for sustainable food grain productiuon [sic] in dry regions

Due to unavoidable, prolonged irrigation with marginal quality water, secondary salinization of irrigated soils in Pakistan has necessitated to a need for better understanding of the water management alternatives. Although H2SO4 and gypsum have far been recognized for their benefits in treating brackish water but during field trials, their relative performance still remains controversial for counteracting the Na-hazards in soil/water system. As alternative sulfur burners are also being marketed but up till now there is not even a single field study published in some journal about their efficiency and economical viability for the treatment of brackish water. Therefore a field study was carried out to compare the effectiveness of sulfurous acid generator (SAG) and other water/soil applied amendments on a normal, calcareous, well drained, sandy loam soil. Rice 2001, wheat 2001-02, and rice 2002 were planted in rotation during the experimentation period with a total of 54 treated and 8 untreated irrigations (each of 7.5 cm). Tube well water used had EC = 3.24 dS m-1, SAR=17.23 and RSC = 5.44 mmolc L-1. The treatments were: T0) Brackish tube well water without any amendment; T1) All irrigation with water passed through SAG; T2) Alternate irrigation-one of SAG treated and one of tube well water, T3) One irrigation with SAG treated water and two with untreated tube well water; T4) FYM @ 15 t ha-1yr-1; T5) Soil applied gypsum to each crop equivalent to affect a decrease in WRSC of tube well water treated with SAG, and T6) H2SO4- fertigation at each irrigation equivalent to affect a decrease in RSC of tube well water with SAG. Water analysis after treatment with SAG (an average of 20 irrigations) revealed that SAG treatment affected only one parameter i.e. water RSC from 5.44 to 3.55, and had no beneficial effect on SARiw and ECiw. After three crops, a minor decrease (up to 2.5%) and increase (up to 5.3%) in soil pHs over initial values was noted at 0-15 & 15-30 cm depth. After three crops the soil ECe and SAR were maintained below the threshold levels and the treatments had non-significant differences. On the basis of three crops, net benefit was maximum, from T4 followed by T5, T3, T0, T2, T6 and T1. The use of sulfur burner/ sulfuric acid was found to be 5 times costlier than gypsum in our study. It is concluded that soil application of gypsum and/or farmyard manure to counter the sodic hazards of irrigation water will be useful as well as economical for rice-wheat rotation on a normal, calcareous well drained soil. However, for fine textured soils with low infiltration rates, to expect similar situation might not be correct for which additional studies are imperative

Step-by-step Guideline for disease-specific costing studies in low and middle income countries: a mixed methodology.

__Abstract__ BACKGROUND: Disease-specific costing studies can be used as input into cost-effectiveness analyses and provide important information for efficient resource allocation. However, limited data availability and limited expertise constrain such studies in low- and middle-income countries (LMICs). OBJECTIVE: To describe a step-by-step guideline for conducting disease-specific costing studies in LMICs where data availability is limited and to illustrate how the guideline was applied in a costing study of cardiovascular disease prevention care in rural Nigeria. DESIGN: The step-by-step guideline provides practical recommendations on methods and data requirements for six sequential steps: 1) definition of the study perspective, 2) characterization of the unit of analysis, 3) identification of cost items, 4) measurement of cost items, 5) valuation of cost items, and 6) uncertainty analyses.Please provide the significance of asterisk given in table body. RESULTS: We discuss the necessary tradeoffs between the accuracy of estimates and data availability constraints at each step and illustrate how a mixed methodology of accurate bottom-up micro-costing and more feasible approaches can be used to make optimal use of all available data. An illustrative example from Nigeria is provided. CONCLUSIONS: An innovative, user-friendly guideline for disease-specific costing in LMICs is presented, using a mixed methodology to account for limited data availability. The illustrative example showed that the step-by-step guideline can be used by healthcare professionals in LMICs to conduct feasible and accurate disease-specific cost analyses

Homocysteine and folate status in methotrexate-treated patients with rheumatoid arthritis.

Contains fulltext : 142827.pdf (publisher's version ) (Closed access)OBJECTIVE: To study (i) the influence of methotrexate (MTX) therapy on homocysteine and folate metabolism in patients with rheumatoid arthritis (RA), (ii) the influence of the C677T mutation in the methylenetetrahydrofolate reductase gene (MTHFR) on the change in plasma homocysteine levels during MTX treatment, and (iii) the interference of folate and homocysteine metabolism with the efficacy and toxicity of treatment with MTX. METHODS: The 113 patients enrolled in this study were participating in a 48-week, multicentre, double-blind, placebo-controlled study comparing the efficacy and toxicity of MTX treatment with and without folic or folinic acid supplementation. The MTX dose was 7.5 mg/week initially and increased to a maximum of 25 mg/week if necessary. Concentrations of total folate, 5-methyl tetrahydrofolate (in serum and in erythrocytes) and of homocysteine, cysteine and cysteine-glycine and the MTHFR genotype were determined before the start of the study, after 6 weeks, and after 48 weeks or on withdrawal from the study. Blood was drawn from fasting patients at a standardized time in the morning, 16 h after intake of MTX. The laboratory results were related to parameters of efficacy and toxicity of MTX treatment. RESULTS: Baseline values were distributed equally in the three treatment groups. The mean plasma homocysteine level (normal range 6-15 micromol/l) before the start of MTX was relatively high in all groups: 15.4 micromol/l [95% confidence interval (CI) 13.5 to 17.2] in the MTX plus placebo group (n=39), 14.3 micromol/l (95% CI 12.2 to 16.4) in the MTX plus folic acid group (n=35) and 15.9 micromol/l (95% CI 13.7 to 18.1) in the MTX plus folinic acid group (n=39). After 48 weeks of MTX therapy, the mean homocysteine level showed an increase in the placebo group (+3.6 micromol/l, 95% CI 1.7 to 5.6). In contrast, a decrease was observed in the groups supplemented with folic or folinic acid (folic acid, -2.7 micromol/l, 95% CI -1.4 to -4.0; folinic acid, -1.6 micromol/l, 95% CI -0.1 to -3.0). The differences in the change in plasma homocysteine level between the placebo group and each of the two folate-supplemented groups were statistically significant (P<0.0001), contrary to the difference between the folic and folinic acid groups (P=0.26). Linear regression analysis showed that the change in plasma homocysteine level was statistically significantly associated with folic or folinic acid supplementation (P=0.0001) but not with the presence or absence of the C677T mutation in the MTHFR gene. Homozygous mutants had a higher plasma homocysteine concentration at baseline. No relationship was found between the change in disease activity and the change in homocysteine concentration or the mean homocysteine concentration after 48 weeks of MTX therapy. Toxicity-related discontinuation of MTX treatment was not associated with the change in homocysteine concentration. CONCLUSIONS: Low-dose MTX treatment in RA patients leads to an increased plasma homocysteine level. Concomitant folate supplementation with either folic or folinic acid decreases the plasma homocysteine level and consequently protects against potential cardiovascular risks. No relationship was found between the change in homocysteine concentration and the presence or absence of the C677T mutation in the MTHFR gene. Homocysteine metabolism was not associated with efficacy or toxicity of MTX treatment