நீரியல்: தற்போதைய ஆராய்ச்சி

Background: India witnessed a sharp decline in rainfall during the decades of 1991-2000 and 2001-2010. But rainfall started improving during the decade 2011-2020 and by the year 2020, the annual rainfall of the country almost became equal to the long period average annual rainfall. Although overall rainfall improved, yet, the present analysis shows that in general, the states in northwest and central India, like Punjab, Haryana, and Uttar Pradesh are facing a remarkable downward trend in seasonal (monsoonal) and annual rainfalls both. The states of the western region of the country, like Rajasthan and Gujrat, are witnessing an upward trend in both seasonal (monsoonal) and annual rainfalls. States of southern India are not much affected.

The present analysis also shows that despite no significant change in the net annual groundwater recharge and annual groundwater draft from 2004, the numbers of over-exploited, critical, and semi-critical blocks rose exponentially after 2011. Further, different groundwater assessments from 2004 show no significant increase in annual groundwater draft, according to a report of the United Nation, groundwater abstraction continued to rise sharply in India. Thus, there seems no compatibility between annual rainfall, annual recharge, annual draft, and numbers of OCS blocks indicating serious discrepancies in groundwater assessment methodology and requiring a serious review of groundwater assessment methodology and norms being adopted in various states of India. Due to declining rainfall in some of the major food grain-producing states, the balance of water distribution in the country is shifting and it may become more prominent in the years to come. India is already the largest abstractor of groundwater in the world and in the above scenario, there will be tremendous pressure on groundwater in the future. The suggested actions which may counter the looming crisis in the country, particularly in north-western and central Indian states, include increasing forest cover up to 20% in the next 25 years in poorly forested states, limiting area under water-guzzling greenhouse producing gas crops, starting land subsidence survey in cities, limiting groundwater abstraction and injecting water into aquifers, launching group schemes of drip and sprinkler irrigation on a large scale using existing tube-wells/wells, searching the alternative source of wastewater by developing integrated facilities to retrieve, treat, store, and transport wastewater, transferring groundwater from groundwater surplus areas to scarce areas enacting comprehensive central law on groundwater, improving water and agriculture resource efficiency through the Internet of Things, cloud and sensor-based network, mapping and time-bound renovation of large traditional water bodies (>1 hectare), revisiting groundwater assessment methodology and norms, quantifying static groundwater resource, developing heat tolerant and less water consuming crops and changing food habits.

Dry season irrigated rice production in northern Ghana is often hampered by lack of sufficient water in dams and reservoirs to meet the crop and irrigation water requirements under continuous flooding. In some years, rice farmers are forced to change their cropping repertoire and move to vegetable production. This situation calls for development of efficient water application and saving methods on the field. The objective of this study was to assess the effects of different water saving irrigation applications to improve over continuous flooding used on dry season rice fields. Two years of experiments were conducted using a randomised complete block design with 4 replications at golinga irrigation scheme in 2017/2018 and 2018/2019 dry seasons, respectively. The treatments were as follows: Alternate Wetting and Drying (AWD 10) at 10 cm water-table drop below the soil surface; AWD 15 at 15 cm drop of water-table below soil surface; Continuous Flooding (CF) from 2 to 10 cm depth of water above soil surface, used as control; Intermittent Flooding (IF) at 5 cm of water-table drop below the soil surface and System of Rice Intensification (SRI). A 115 days maturity rice variety Gbewaa (i.e. Jasmine 85) was used for the experiments. Seedlings were transplanted at spacing of 20 cm × 20 cm at one seedling per stand in 27 m² plots. Data were collected on plant height, number of tillers, days to 50% heading, yields and yields related parameters. The results showed that all the parameters with the exception of maximum tiller count, showed significant difference between SRI and the rest of the treatments. AWD 10 and IF are recommended as most suitable for adoption by rice farmers in the Northern Region of Ghana.

Background: The Nile Delta aquifer in Egypt subjected to a severe seawater intrusion problems because of the excessive pumping over the last several decades. The seawater has intruded the aquifer up to a distance more than 70.0 km measured from the shoreline along the bottom boundary of the aquifer. Climate change and the rise of sea level will affect the groundwater quality in the Nile Delta aquifer in two methods. First, low and flat lands along the shoreline will be submerged with seawater and the aquifer below these lands will be damaged. Second, pressure heads of sea water will increase causing more intrusion. Seawater intrusion is a process which seawater infiltrates into freshwater aquifers due to natural processes or human activities. Seawater intrusion is caused by decreases in groundwater levels as a result of excessive pumping or by rises in seawater levels as a result of climate change. The salt water rises 40 m for every 1 m of freshwater depression and forms a cone of salt water. The effects of intrusion on water quality not only belongs to the pumping well sites, but also at other well sites, and undeveloped parts of the aquifer. The problem of seawater intrusion is mainly conditioned by three factors: first, the difference between the densities of the fresh and salt water, second, the hydrodynamic properties of the aquifer and third, the flow that the aquifer discharges into the sea. The first two factors are intrinsic to the seawater intrusion problem regardless of the climate in the region. Furthermore, these two parameters are established, and cannot be affected by the usual human activities. The flow that the aquifers discharge into the sea is conditioned by natural conditions (from rainfall) or artificial recharge (mainly from irrigation and canals networks) and by pumping. Therefore, anthropogenic actions can make some modifications. The most prevailing technique is to increase the flow of groundwater from the aquifers towards the sea. In this paper (ARC GIS) program is used to prepare the required maps for the 3-D models (MODFLOW + SEWAT) which are used to simulate saltwater intrusion in the Nile delta aquifer. The amount of water pumped from the Nile delta aquifer through wells belongs to 2008. The recent shore line of the Mediterranean sea is used. The results of the simulation show that the Equi-concentration line 35 reaches 81 km in the east of the Nile delta, 93 km in the middle and 68.5 km in the west for base case. The Equi-concentration line 35 of this simulation is compared with the Equi-concentration line of 1960, 1980 and 1992. It is observed that the creep of the iso saline water occurs at the west and the middle of the Nile delta compared to these years.

Background: Studies on water security, climate change, land use, and land cover changes are, therefore, carried out all over the world, including in Brazil, where a growing body of related literature has been published in various scientific journals. On the one hand, performance analysis and science mapping are two main procedures in bibliometric analysis. They can conveniently show an important quantitative perspective to quickly learn the state, characteristics, and trends of research topics by providing robust indicators to reveal the dynamic mechanics hidden behind the number. The data of research publications on “water security (WS)”, “climate change (CC)” and “land use and land cover changes (LULC)” are all of them linked to “Brazil”, from the Web of Science Core Collection database and Scopus dataset were collected between 1990-2019. As well as, a critical review of the Brazilian National Water Security Plan (PNSH), aims to examine different approaches to water security under climate change and land use/land cover changes, and water governance in the context of the PNSH. Our results highlighted that research on CC and LULC has increased sharply over the past decade, while the WS concept starts to appear in 2014. Summarized information on retrieved WS, CC, LULC studies, such as yearly publications timeline, most popular publication platforms, salient keywords analysis, hot topics, cooperation level, and top-cited articles. That analysis provided the clues to discover the current research emphases and mapping trends of research topics. High rates of deforestation due to the expansion of agricultural lands, the water-food-energy nexus, strongly promoted climate change and land use/ land cover changes research. However, the simultaneous effect of the two stressors on water resources is not often comprehensively investigated. As well as, the environmental consequences of these transformations are still poorly assessed but are strongly needed to support future planning and management of water resources, to mitigate these impacts.

Background: In this study watershed was delineated by using ArcGIS 10.4 for Lake Chamo basin and necessary procedures was described. Area for Lake Chamo basin was calculated and the result shows that the total area contributes flow to Lake Chamo was 8112.98 Kilo meter square based on the delineated water shed. Location map for the water shed was also created. This finding are important for water resource planning and decision making at Sub water shed level to minimize problems in the water shed and take remedial action for water resource planning and management to utilize the limited resource optimally. It was also important to scholars to use as the source of data in the water sheds to conduct further research in the watershed.

Background: The research was aimed at ascertaining the quality of Boreholes water in some selected institutions in Gashua Town namely; Federal University Gashua, Umar Suleiman College of Education, Gashua and Ramat UBE School, Gashua. The results highlighted vital information on the potability of water samples sampled in Hand Pump water borehole sources. Some physico-chemical parameters were assessed using water quality tests instruments and Spectroscopic equipment’s. The parameters analysed are: pH, Electric Conductivity, Turbidity, TDS, Sulphate, Total Chlorine, Nitrate, Nitrite, Magnesium, Manganese, Molybdenum, Chromium, Iron, Copper, Lead, Nickel and Cadmium. The findings of the research indicated the potability of the water, its usability domestically, agriculturally and industrially.