Semi-arid Region Of South India Research Articles

Evaluation of non-carcinogenic causing health risks (NCHR) associated with exposure of fluoride and nitrate contaminated groundwater from a semi-arid region of south India.

Groundwater is the foremost resource for drinking water supply in arid and semi-arid regions of the world, and also intake of contaminated drinking water is the major source for creating a several health risk for humans. To estimate the groundwater suitability for drinking and also to measure the non-carcinogenic health risk for infants, children, and adults, a total of 35 groundwater samples were collected from the semi-arid region of India and analyzed major ions including fluoride and nitrate. The results revealed that the concentration of fluoride ranges from 0.6 to 3.6mg/L and is about 2.4 times higher than the maximum allowable limit of 1.5mg/L for drinking water purposes. And nitrate contents varied from 17 to 120mg/L in which 54.29% of the groundwater samples exceeded the recommended limit of 50mg/L. The estimated individual non-carcinogenic health risk (INCHR) frequency is evidently displayed that intake of higher concentration of nitrate creates the greater detrimental health effects than fluoride. The contribution of individual non-carcinogenic health risk (INCHR) of nitrate is greater detrimental health effects than the fluoride. The results of total non-carcinogenic health risk (TNCHR) reflect the infants and also children were found to be more susceptible towards fluoride and nitrate-associated health risks in the investigated region. Fluoride-bearing minerals and different anthropogenic sources such as septic tank leakages, nitrogen fertilizers, domestic, agricultural, and animal wastes played a vital role in groundwater pollution and thereby non-carcinogenic human health risks. Therefore, a proper sustainable future plan is most important to mitigate the fluoride and nitrate contamination in the groundwater of the study region.

Impact of Rainfall Trend on Irrigated Agriculture of Narayanapura Command in a Semi-Arid Region of South India

Water demands have been exacerbated by the uncertainty in rainfall occurrences and distribution due to various factors in a changing climate and growing population. The irrigation sector has the highest water demand, accounting for 85 percent of total water use in Karnataka. Rainfall plays a critical part in meeting irrigation needs. To effectively allocate and manage water resources for command area management, examining rainfall patterns, distribution of rainfall trends, both regional and temporal variations is necessary. Hence, the primary focus of this research is to investigate the impact of rainfall trends on agricultural water requirements for a typical study area in semi-arid region.
 To assess the rainfall trend, time-series statistical trend tests called Mann–Kendall (MK) test and the Innovative Trend Analysis (ITA) approach are used to examine the spatio-temporal distributions of long-term rainfall patterns for the Narayanapura command region. The results are then geo-processed to examine the spatial distribution of trends using the isohyetal concept. The findings illustrate the spatial distribution of rainfall trend for the command in a semi-arid region on a monthly, monsoon, and annual basis.
 Spatio-temporal analyses from both methodologies indicates the trend in rainfall pattern is decreasing annually and in monsoon months, with a rising trend for pre-monsoon showers. The trend variation pattern also reveals periodic oscillation alignment in the direction of south-west monsoon movement. According to MK test results, monsoon rainfall is anticipated to decrease by 12 percent by 2047, and by 21 percent from ITA results. Further, impact analysis indicates that, for every unit millimeter of rainfall deficit, there would be a 62 Ha-m increase in irrigation water demand.

Optimal Annual Allocation Model of Large Storage Based Irrigation Project by Multi Level Approach

The effective management of water available for irrigation in arid and semi-arid regions has increased in importance due to limited water supply. The need for allocation of water resources optimally in a water limiting condition has already been recognized, and much research has been carried out. In the present study, an annual irrigation planning model is formulated for Nagarjuna Sagar Project command in the semi-arid region of South India dealing with optimal allocation of annual available water among command areas of each main canal taking off from the reservoir and reallocating the available land and water of each command area to different seasons of a year and finally allocating the available land and water of each season among crops grown in that season, maximizing the total annual benefit of the project. The problem is solved in three stages. In the first stage, fortnightly crop water requirements are calculated from the evapotranspiration model by Penman – Monteith method. In the second stage, seasonal crop water production functions are developed using the single crop intraseasonal allocation model for each crop of all seasons. In the third stage, allocations of area and water are made at seasonal, interseasonal and at reservoir levels by deterministic dynamic programming, maximizing the net annual benefit from the project. Optimal cropping pattern and irrigation water allocations are made with full and deficit irrigation strategies for various levels of probability of exceedences of expected annual water available and results obtained are discussed.

Identification of artificial groundwater recharge zones in semi-arid region of southern India using geospatial and integrated decision-making approaches

The present study integrates various decision-making methods viz. Fuzzy Logic (FL), Frequency Ratio (FR), Analytical Hierarchy Process (AHP) to delineate the artificial groundwater recharge zones (AGRZs) in semi-arid region of south India. Eight criterions used in this process, including lithology, soil types, lineament density (LD), drainage density (DD), vadose zone (VZ), rainfall, land use/ land cover (LULC), and slope. All of these criteria and their sub-criteria used to derive weights for different thematic layers and combined using a geospatial method to classify AGRZs. The resultant map was categorised into five classes: very poor, poor, moderate, good and very good. The FL, AHP, FR, and integrated approaches were validated against groundwater fluctuation data using receiver operating characteristic (ROC) and field AUC [Area Under the Curve] approaches, showed an accuracy of 72%, 76% and 78% and 82%. As a result, the output of the integrated models outperforms that of the FR, FL and AHP models. Fuzzy reasoning and AHP methods rely on assigning a relative score based on the significance of the variables, which necessitates extensive knowledge of the criterions. FR, on the other hand, is simpler and more reliable since it does not rely on user-based scoring for the various criterions. The results of this study can be useful for decision makers responsible for the sustainable management of groundwater resources.

Coppicing impact on the essential oil yield and its chemical composition of lemongrass cultivars of the genus Cymbopogon under the semi-arid region of South India

A study was carried out at CSIR-CIMAP, RC. Hyderabad (India) to study the impact of coppicing time on the oil percent and its chemical composition of different cultivars of lemongrass using a randomized block design. The freshly harvested herb was used for the hydro-distillation for essential oil, and subsequent chemical analysis. The chemical components identification of the essential oil was performed by GC–MS. In the results coppicing time influenced significant changes in the essential oil content, essential oil yield, and its chemical composition especially, total citral, and geraniol content. The four top rankers varieties/cultivars of lemongrass for the essential oil yield were CIM-Shikhar > Krishna > CKP-25 > CIMAP-Suwarna; for the essential oil content CIM–Shikhar > Krishna > CIMAP-Suwarna > Praman; for total citral content Nima > CIM–Shikhar > Krishna > Pragati, and for the total geraniol content Himrosa > CN-5 > Tawirosa > Kalam, respectively. Therefore, we can recommend these varieties/cultivars for commercial cultivation in large areas under the semi-arid region of south India.

Appraisal of subsurface hydrogeochemical processes in a geologically heterogeneous semi-arid region of south India based on mass transfer and fuzzy comprehensive modeling.

The main aim of the present study was to examine the quality of the groundwater and decipher the sources of groundwater fluoride through mass balance modeling based on fluoride exposure in a geologically heterogeneous semi-arid region of southern India. This was achieved by hydrogeochemical analysis, graphical methods, and mass transfer modeling approaches. Fuzzy comprehensive technique was applied to evaluate the quality of groundwater for groundwater management. In this regard, 61 groundwater samples were obtained from open wells and bore wells and analyzed for different physicochemical parameters. The major cation and anion abundances follow the order Na+ > Ca2+ > Mg2+ > K+ and Cl- > HCO3- > SO42- > NO3- > PO43-. About 88.4% and 34.4% of the total water samples were dominated with Na+ and Cl- ions in this region, respectively. The fluoride level in groundwater ranged from 0.10 to 3.30mg/l with a mean value of 1.04mg/l. Nearly 25% of the groundwater samples collected from 15 villages showed fluoride concentrations exceeding the maximum permissible limit of 1.5mg/l as per the World Health Organization recommendations for human intake. More than 85% of the samples fell under strong acid (Cl- and SO42-) type. The amount of groundwater salinization in this region was 70.5% since the Revelle index (RI) was excess in the groundwater samples (RI > 0.5meq/l). Silicate weathering, cation exchange, and gypsum dissolution were the dominant geogenic processes in the aquifer system influencing groundwater chemistry and nullified the possibility of carbonate dissolution. Saturation indices revealed the contribution of sequestration of CaCO3 in F- enrichment. Total dissolved solids showed strong positive correlations with Na+, Ca2+, Mg2+, Cl-, SO42- and NO3- indicating the contribution of anthropogenic inputs to groundwater chemistry in addition to geogenic sources. The results of the fuzzy comprehensive method indicated that 33% of the groundwater samples fell under fair water type, 2% and 11% of the samples fell under poor and very poor quality water types, respectively. Therefore, this work will be helpful for the decision-makers to plan for the sustainable management of groundwater resources.

Sobol sensitivity approach for the appraisal of geomedical health risks associated with oral intake and dermal pathways of groundwater fluoride in a semi-arid region of south India.

The main objective of the present investigation is appraisal of human health hazard based on the intake and dermal contact of fluoride enriched potable groundwater used for rural water supply in a semi-arid region (Shanmuganadhi River basin) of south India. A variance decomposition based Sobol sensitivity method was used to assess the relative contribution as well as interaction of input variables for both oral and dermal models. Three different scores were evaluated: FOE (first order effect), SOE (second order effect) and TE (total effect) for different age groups of population including gender (kids, women and men). The spatio-temporal mapping indicates that about 26% of water supply wells exceeded the recommended limit (WHO) of fluoride (>1.5mgl-1) for safe intake. These wells spread over 104.03km2 area consisting 16 villages in the basin. To assess the human health risk related to fluoride enrichment in potable water, hazard index (HI) was calculated as per USEPA guidelines. The non-carcinogenic risk based on oral intake ranges from 0 to 1.81, from 0 to 1.59 and from 0 to 1.29 for kids, women and men respectively. Nearly 30%, 21% and 12% of well samples exceeded the upper permissible limit (HI>1) for kids, women and men respectively. The Sobol sensitivity analysis reveals that, Cw (concentration of F- in water) and IR (intake rate) combination plays a vital role in the HQ oral model for the appraisal of health hazard in kids. However, these two parameters have negligible effect on health hazard for adult population (men and women). Therefore, lower age group people especially kids have significant ill effect due to the consumption of fluoride enriched potable water. The model output suggests that body weight (BW) has least effect on health hazard in the lower age group of population. Interestingly 'exposure frequency (EF)' and 'body weight (BW)' have not much effect on health hazards related to dermal contact, and 'skin surface area (SA)' has minimal effect for men (TE=0.92) and women (TE=1.26). However, 'SA' has vital effect for kids (TE=17.39). Because of this, older age group people have more dermal risk than the younger people. Therefore, the HQ dermal results indicate that 49%, 64% and 67% of samples possess non-carcinogenic risk to the kids, women and men respectively.

Modelling the daily reference evapotranspiration in semi-arid region of South India: A case study comparing ANFIS and empirical models

The estimation of evapotranspiration (ETo) is one of the main tools for the control of crop growth and to make a rational use of water resources. To estimate this parameter accurately, it is necessary to have a daily measurement of four meteorological variables, these are: temperature, solar radiation, relative humidity and wind speed. It is not always possible to count on all the variables, that is why there are empirical methods that use a limited number of variables that make an approximate estimate of the ETo value. Each of these models are applicable to different regions with completely different climates. In this paper, a study has been carried out to define the model of ETo estimation that best adapts to the semi-arid region in South India. Two different datasets for the same period from different meteorological stations were used. In addition to the empirical methods for estimating ETo, computer models ANFIS (Adaptive Neuro-Fuzzy Inference System) were implemented. These models consist in the future estimation of a certain parameter by using current variables and a history of variables and past results. The results of this work show that ANFIS 11 model makes the best estimate with RMSD = 0.002 and r = 0.999. The RITCHIE method is the most suitable empirical model for this region, which reaches RMSD = 0.507 and r = 0.851. In addition, ranking of equations is elaborated for both datasets for daily estimates of ETo. Finally, comparison is made with the results for each case and thus confirm or reject the convenience of one model over the rest. To achieve this, a series of statistical indicators were used: Index of agreement (d), MAE (Mean absolute error), SEE (Standard error of estimate) and RMSD (Root mean square difference). Moreover, a sensitivity analysis was performed in order to compare and show the stability of the best models when an error is introduced within the input parameters. In this case, the empirical models demonstrate a better performance than the ANFIS models. This work demonstrates that the Ritchie method is a good estimator of the ETo value for a semi-arid region in southern India. In addition, the results of the ANFIS models are promising and could be used as estimation methods.

The effects of geochemical processes on groundwater chemistry and the health risks associated with fluoride intake in a semi-arid region of South India

This study attempts to establish the effects of subsurface geochemical processes based on the hydrogeochemical attributes of 61 well samples collected in a semi-arid region of South India. The study also provides the health risks associated with the consumption of fluoride-enriched groundwater by the rural people since groundwater is the major source of water supply in the Shanmuganadhi River basin. In this work, water–rock interaction diagrams, an entropy-weighted water quality index (EWQI), and health risk models as per the United States Environmental Protection Agency (USEPA) were prepared to understand the geochemical mechanism behind the groundwater chemistry and its role in impacting health. About 72% of these samples are of mixed Ca2+–Mg2+–Cl− water type, representing a transition from freshwater to brackish water, and 36% of them have fluoride above the permissible limit (>1.5 mg l−1). An evaluation of the hydrogeochemical attributes suggests that silicate weathering, carbonate dissolution and reverse ion exchange mostly control the hydrochemistry of the groundwater. The EWQI characterizes about 30% of these samples as unsuitable for drinking and another 49% as of moderate quality. Human health risks were evaluated by dividing the population into seven different age groups and estimating the hazard quotient (HQ) and total hazard index (THI) from intake and dermal contact with fluoride-rich groundwater. The groundwater of this region poses a higher risk for the younger population compared to the adults. About 79% of these groundwater samples pose a health risk to 5–12 month-old infants and only 36% of the samples could be potentially hazardous for adults >23 years old. Our results suggest that the ADDdermal pathway indicates less risk compared to the ADDintake estimations.

Controlling factors and mechanism of groundwater quality variation in semiarid region of South India: an approach of water quality index (WQI) and health risk assessment (HRA).

The study region comprises fractured granitic, basaltic and lateritic aquifer system constituted by Precambrian rocks. Groundwater is the primary source for drinking and household needs. Its quality is a big issue in the three aquifers, which are mostly of human health concern. Many developing regions suffer from lack of safe drinking water, thereby health problems arise in many parts of the regions, and Telangana state is one of them. For this reason, 194 groundwater samples were collected and analyzed for fluoride, nitrate, chloride and other physicochemical parameters. The concentrations of fluoride (F-), nitrate (NO3-), magnesium (Mg2+), total dissolved solids and total hardness are above the acceptable limits for drinking purposes, prescribed by the World Health Organization. The higher concentrations of fluoride and nitrate in drinking water cause health hazards, and above 50% of the groundwater samples are not suitable for drinking purposes with respect to fluoride and nitrate. Weathering of rocks and dissolution of fluoride-bearing minerals can be a cause for higher fluoride concentrations, while anthropogenic sources are one of the major reasons for higher nitrate concentrations in the study area. Groundwater suitability for irrigation suggests that more than 90% of the groundwater sampling locations are suitable for irrigation. In addition, health risk assessments were evaluated by using the United States Environmental Protection Agency model, to determine the non-carcinogenic risk of fluoride and nitrate in drinking water for adults (females and males) and children. The ranges of hazard index in all sampling locations are varied from 0.133 to 8.870 for males, 0.146 to 10.293 for females and 0.419 to 29.487 for children, respectively. The health risk assessment results indicated that children were more exposed to health risk, due to the intake of high contaminated drinking water with respective of nitrate and fluoride in the study region.

Spatial distribution, exposure, and potential health risk assessment from nitrate in drinking water from semi-arid region of South India

Elevated nitrate concentration in groundwater is a worldwide problem. Continuous exposure to high levels of nitrate in groundwater may cause adverse health effects among residents who use groundwater for consumption. Therefore, this study was conducted to identify the nitrate distribution and its potential health risk assessment from semi-arid region of Peddavagu in Central Telangana (PCT), South India. Groundwater samples were collected from thirty five locations and analyzed for nitrate and other water quality parameters. Nitrate (NO3-) in groundwater was observed to vary from 17 to 120 mg/L, with a mean of 58.74 mg/L. About 57% of samples exceeded the maximum acceptable limit of Indian drinking water standard. About, 40% of groundwater samples drinking water quality index (DWQI) is good, while 60% of groundwater falls in poor quality for drinking purposes. Health risk maps were created based on hazard quotient to quantify the potential health risk of the residents using US Environmental Protection Agency (US EPA) health risk assessment model. Health risk assessment revealed that mean total hazard index (HItotal) for men, women, and children were found as 1.42E + 00, 1.67E + 00, and 1.95E + 00, respectively. Results exhibited that children are at high health risk than men and women in the PCT. Further, the human exposure to the NO3- contaminated water was above the critical limit of non-carcinogenic risk.

Groundwater quality and associated health risks in a semi-arid region of south India: Implication to sustainable groundwater management

Groundwater is the only water source in the Siddipeta-Vagu (SDV) region, India, and its quality is vital as it is the primary factor determining the groundwater suitability for drinking and irrigation uses. In this study, 51 groundwater samples were collected to assess the suitability of groundwater for domestic and irrigation purposes and to estimate the potential impacts of groundwater contaminants on human health. Discussions on sustainable groundwater management in this study area were also reported. The groundwater quality of the SDV region is severely affected by geogenic sources and urbanization as specified by the distribution of fluoride and nitrate. The results reveal that the highest concentration of nitrate is 348 mg/L and fluoride is 3.7 mg/L in the study region. The nitrate and fluoride appear as the principal problem affecting safe drinking water in the SDV region. The foremost hydrochemical facies indicate that alkalis exceed alkaline earth and strong acids exceed weak acids in groundwater. The results of sodium adsorption ratio (SAR), percentage sodium (%Na), magnesium hazard ratio (MHR), Kelly’s ratio (KR), and residual sodium carbonate (RSC) show that most of the groundwater samples are suitable for irrigation purposes. Non-carcinogenic health risks due to nitrate and fluoride exposure through consumption of drinking water were also evaluated using the USEPA method. Results indicate that the infants are the most susceptible groups to nitrate and fluoride through drinking water in the study area. Therefore, necessary groundwater management strategies should be implemented to control the groundwater pollution and also to protect the populace health in the study region.

Groundwater Quality for Drinking and Irrigation Purposes and Potential Health Risks Assessment: A Case Study from Semi-Arid Region of South India

To determine the groundwater quality in the rapidly urbanizing region of Telangana State, South India, 194 groundwater samples were collected and analyzed for evaluating the groundwater quality using a geographic information system (GIS) technique. Cations, viz., calcium, magnesium, sodium, potassium; and anions such as bicarbonate, carbonate, chloride, nitrate, sulfate, and fluoride were analyzed using standard procedures. The nitrate concentrations varied from 4 to 440 mg/L, with a mean of 73 mg/L. It is noticed that 48% of the groundwater samples showed nitrate concentrations higher than the maximum permissible limit recommended by World Health Organization (WHO) and Bureau of Indian Standards. The high fluoride concentrations in about 57% of the samples exceeded the maximum permissible limit of 1.5 mg/L. High fluoride concentrations are attributed to geogenic source i.e., rock–water interactions with fluorine-bearing minerals present in the granites of the study region. Interpretation of chemistry using Piper diagram indicated that Ca2+–Mg2+–Cl−, Ca2+–Na+–HCO3− and Ca2+–HCO3− were the most predominant water types in the study region. The data plotted in the US Salinity Laboratory diagram which revealed that most of the samples fell in the category of C2S2 and C2S3, indicated that the groundwater suitable for irrigation purposes. In additional, health risk assessments were performed and evaluated using the Unites States Environmental Protection Agency (US EPA), to determine the risk of noncarcinogenic disease due to fluoride and nitrate in drinking water. Ingestion health risks were estimated for adults (females and males) and children. Results indicated that children were more exposed to health risk, due to intake of high contaminated drinking water with respective of nitrate and fluoride in the study area.

Evaluation of groundwater quality for irrigation in a semi-arid region of South India

Groundwater quality was evaluated for irrigation purpose by collecting the groundwater samples from 36 locations during pre- and post-monsoon seasons. These groundwater samples were analyzed for physico-chemical parameters like pH, EC, TDS, major cations, and anions. Furthermore, irrigation quality indices like salinity hazard, chloride hazard, magnesium hazard, carbonate and bicarbonate hazard and sodium hazard were calculated using the analytical results. These parameters were compared with standard limits for irrigation use for the prevailing crops. The hydrochemical results indicate that the groundwater in the study area is neutral to slightly alkaline in nature. Based on the EC and TDS classification, most of the groundwater samples are falling under medium salinity hazard category. The order of abundance of major anions and cations in groundwater was found as $${\text{HCO}}_{3}^{ - }>{\text{C}}{{\text{l}}^ - }~$$ > $$~{\text{NO}}_{3}^{ - }~$$ > $$~{\text{SO}}_{4}^{{2 - ~}}$$ > $$~{\text{CO}}_{3}^{{2 - }}>{{\text{F}}^ - }$$ and $${\text{N}}{{\text{a}}^+}~$$ > $$~{\text{C}}{{\text{a}}^{2+}}~$$ > $$~{\text{M}}{{\text{g}}^{2+}}~$$ > $${{\text{K}}^+}$$ . The Chadha’s diagram revealed the dominance of $${\text{N}}{{\text{a}}^+} - {\text{HCO}}_{3}^{ - }$$ , mixed $${\text{C}}{{\text{a}}^{2+}} - {\text{M}}{{\text{g}}^{2+}} - {\text{C}}{{\text{l}}^ - }$$ , and mixed $${\text{C}}{{\text{a}}^{2+}} - {\text{M}}{{\text{g}}^{2+}} - {\text{HCO}}_{3}^{ - }$$ and $${\text{N}}{{\text{a}}^+} - {\text{C}}{{\text{l}}^ - }$$ types of hydro-geochemical facies. Based on the EC and SAR, classification more than 50% of the samples is falling under slight to moderate reduction in infiltration rate category in both seasons. The study revealed that most of the water samples are exceeding the critical levels of irrigation water quality and it may require careful management to growth suitable crops in the study area. In addition, the study also points out that usage of such a high TDS groundwater for irrigation may cause soil salinity.

Does the employment guarantee scheme stabilize household incomes in rural India?

Our analysis, based on the ICRISAT panel survey of villages in the semi-arid region of south India, confirms the income stabilizing effect of the Employment Guarantee Scheme in India. Variability of household income is measured by an unconditional variance of residuals of an income equation. A (variant) of Heckman's sample selection model is employed to allow for the endogeneity of EGS participation and to assess its income stabilizing role. The (instrumented) EGS participation reduces the residual variance of household income, implying consequent income stabilization.

Optimal Irrigation Planning under Water Scarcity

In this study optimal irrigation planning strategies are developed for the Nagarjuna Sagar Right Canal command in the semiarid region of South India. The specific objective of the study is to allocate the available land and water resources in a multicrop and multiseason environment and to obtain irrigation weeks requiring irrigation of a fixed depth of 40 mm. The problem is solved in four stages. First, weekly crop water requirements are calculated from the evapotranspiration model by the Penman-Monteith method. Second, seasonal crop water production functions are developed using the single-crop intraseasonal allocation model for each crop in all seasons. Third, allocations of area and water are made at seasonal and interseasonal levels by deterministic dynamic programming, maximizing the net annual benefit from the project. And fourth, once optimal seasonal allocations have been attained, irrigation scheduling is performed by running a single-crop intraseasonal allocation model. Optimal cropping pattern and irrigation water allocations are then made with full and deficit irrigation strategies for various levels of probability of exceedance of the expected annual water available. The results reveal that the optimization approach can significantly improve the annual net benefit with a deficit irrigation strategy under water scarcity.

Assessment of groundwater quality for drinking and irrigation purposes: a case study of Peddavanka watershed, Anantapur District, Andhra Pradesh, India

In India, the quantity and quality of water available for irrigation is variable from place to place. Assessment of water quality has been carried out to determine the sources of dissolved ions in groundwater. Quality of groundwater in a 398 km2 Peddavanka watershed of a semi-arid region of south India is evaluated for its suitability for drinking and irrigation purposes. The middle Proterozoic Cuddapah Supergroup and Kurnool Group of rocks underlie most of the watershed. The main lithologic units consist chiefly of quartzite, limestone, and shale. Seventy-six water samples were collected from open-wells and bore-holes. Water samples were collected representative of the post-monsoon (winter) and pre-monsoon (summer). The quality assessment is made through the estimation of Ca2+, Mg2+, Na+, K+, Cl−, SO 4 2− , CO 3 2− , HCO 3 − , total hardness as CaCO3, TDS, EC, and pH. Based on these analyses, parameters like sodium adsorption ratio, % sodium, residual sodium carbonate, non-carbonate hardness, potential salinity, Kelley’s ratio, magnesium ratio, index of base exchange and permeability index were calculated. According to Gibbs‘ ratio samples in both seasons fall in the rock dominance field. The overall quality of waters in the study area in post-monsoon season is high for all constituents ruling out pollution from extraneous sources.

1986年度秋季学術大会シンポジウム 「砂漠化」の地理学

Desertification has been a universal issue since it was discussed at UNCOD (United Nations Conference on Desertification) in 1977. The word desertification is defined here as land and vegetation degradation at various parts of the world including humid region as well as arid and semi-arid regions. This symposium aimed at examining the present situation of those areas suffered from desertification and studying out preventive measures of this phenomenon. The following subjects were set up: 1. Climatic variation and desertification. 2. Water use and salinization. 3. Agro-pastoral land use and degradation of land. 4. Natural environment and change in land use. 5. Preventives of desertification and suggestions for environmental management. Submitted studies are as follows: [Climatic variation and desertification] Tanaka, M. (Meteorological Research Institute): Recent climatic change and increased aridity in the tropical regions. Iwasaki, K. (Hokkaido University): Climatic fluctuations and desertification in Australia. [Water use and salinization] Matsumoto, S. (The University of Tokyo): Water utilization and salts accumulation with the agricultural development in arid lands. Takamura, H. (Rissho University): Desertification in Zambia and some problems of ground-water rising in Qatar. [Agro-pastoral land use and degradation of land] Takeuchi, K. (The University of Tokyo): Vegetation-ecological discussion on the ‘desertification’ phenomena in the southern part of semi-arid Australia. Tase, N. (University of Tsukuba): Background of desertification and environmental management in the U. S. A. Tamura, T. (Tohoku University): Development of pseudo-semiarid landscape in humid tropical Africa. Yasuda, Y. (University of Hiroshima): A study of the mechanism about the continual devastation of forest in Ege Sea region. [Natural environment and change in land use] Fujii, H. (Hyogo University of Teacher Education): On adaptation to the change of natural environment in case of modern agro-pastoral system and traditional agro-pastoral system in West Africa. Fujiwara, K. (University of Hiroshima) and Sadakata, N. (Hokkaido University of Education): Rural development schemes and changes in land use in the semi-arid region of South India. Yamamoto, S. (University of Tsukuba): Some observations on the traditional agricultural systems adapted to the physical environment of the semi-arid region in Northeast Brazil. Goto, A. (Kanagawa University): Traditional agriculture-system in arid and semi-arid area.-The case study of Iran-. [Preventives of desertification and suggestions] Kohno, M. (Kansai University): Desertification and its recovering policy in China. Kobori, I. (Mie University): Desertification and desertification control. Tomita, K. (Japan International Cooperation Agency): Preventives of desertification. [Discussion Opener] Ichikawa, M. (Akikusa Gakuen Junior College): On the present situations and problems of the desertification in the world. Presented subjects were discussed almost to the full. There are few studies, however, based on original data and regional comparison remains to be discussed.