Hydrologie : recherche actuelle

Kivi Plainis located in the northeastern city of Kiviin Ardabil province. Due to the large number of villages in the desert and its people engaged in agriculture and animal husbandry, Study of ground water to determination of the optimal location of wells is important. In this regard, geoelectric technique was used for studies of groundwater quality and quantity of Kivi plain. In this research, the resolution of the subsurface layers, detection of saturated zone, determination of basement, detection of the general direction of groundwater and changes of resistivity in sounding points and profiles have been studied. The number of 196 vertical electrical sounding on nine profiles and the number of 9 sounding in variety points and in vicinity of exploratory wells by schlumberger array in the study area have been taken. "IPI2win" software is used for the interpretation of vertical electrical sounding curves and one-dimensional modeling. By “Res2dinv”, twodimensional modeling and preparation of resistivity section have been taken. According to the results of the interpretation of the data in the study area, sediments inparts of the Middle East and Northern have developed, and from the surface to the depth of alluvium and marl deposits were included. More aquifer layers in marly sand deposits, silt and sand, crushed limestone and salty zones were observed. Basement is included most of marl (with the layers of sandstone and conglomerate), limestone and silt. According to the basement, the topography slope of the area and isopiezecurves, groundwater movement is toward the northeast.

River flood is a natural disaster that occurs each year in the Fogera floodplain causing enormous damage to the human life and property. Overflow of Ribb and Gummara rivers and backwater effects from Lake Tana has affected and displaced thousands of people since 2006. Heavy rainfall for a number of days in the upper stream part of the catchment caused the river to spill and to inundate the floodplain. Three models were used for this research; the numerical weather prediction model (WRF), physical based semi distributed hydrological model SWAT and the LISFLOOD-FP 1D/2D flood inundation hydrodynamic model to forecast the extreme weather, flood and flood modeling. Daily rainfall, maximum and minimum temperature for the forecasted period ranges from 0 to 95.8 mm, 18°C to 28°C and 9°C to 18°C, respectively. The maximum forecasted flow at Ribb and Gummara Rivers have 141 m3/s and 185 m3/s respectively. The flood extent of the forecasted period is 32 km2; depth ranges 0.01 m to 3.5 m; and velocity ranges from 0 to 2.375 m/s. This technique has shown to be an effective way of flood forecasting and modeling. Integrating Rainfall Runoff model with hydrodynamic model provides thus good alternative for flood forecasting and modeling.

Land Use and Land Cover Change (LULCC) is a major driver of environmental problems like water pollution, decreased soil quality, and natural resource scarcity. Measuring LULCC is necessary to better understand the present condition of watersheds. Time series LULCC mapping using Geographic Information Systems (GIS), high-resolution imagery, and field data collection are effective methods for examining LULCC trends. The Mahadev Khola watershed in Bhaktapur, Nepal, acts as a primary source of drinking water for people living within the Bhaktapur municipalitywhich is dominated by forest at higher elevations and agricultural lands and settlements at lower elevations. The purpose of this study was to observe LULCC dynamics within the Mahadev Khola watershed to better understand the social and environmental problems that can arise in consequence. Time series land use maps were created and analyzed using GIS methods. Responses from a survey of local people, as well as interviews from selected key stakeholders, contribute insight into how past scenarios of land use have influenced-and have been influenced by-LULCC. Significant changes in land use were quantified between 2005 and 2014. Results suggest that in this period, total forest area decreased by 6.25%, cultivation area decreased by 14.28% and settlements increased by 156.25%. Survey and interview responses suggest that much of this change is due to agricultural intensification and an increase in chemical fertilizer and pesticide use. Increased agricultural inputs have increased the potential for river and water pollution and long term soil degradation. Urban expansion and development have led to the contamination of rivers with sewage and solid waste, which has increased health risks for local communities. Although total forest area has increased, the species composition has changed-now primarily dominated by Pinus roxburghii. The result of this is a decrease in river water discharge and increase in soil and water acidity. The results of this study are timely and important for analyzing the dynamics between LULCC and watersheds in order to improve future management efforts in Nepal and the Eastern Himalayan region of South Asia.

A study was conducted to evaluate the effect of supplementing Taro (Bolosso-1), Enset corm and Sugarcane stock on feed intake, weight gain and net return of fattening local oxen. Sixteen local un-castrated oxen of about 5 years’ age and average weight of 249 kg were used as Enset corm and Sugarcane. A completely randomized design was used and 4 bulls were allotted to a treatment. The result showed that bulls supplemented with Taro treatment had significantly (P<0.05) higher daily intake of a total dry matter (8.26 kg/bull) and nutrients while the daily intake of fresh grass (5.33 kg/bull) on no supplemented treatment had significantly higher (p<0.05). Bulls supplemented with Taro treatment had significantly (P<0.05) higher average daily weight gain (0.75 kg/bull) and lower feed to gain ratio (11.14). The extent of lean and fat meat per unit of animal implies that the amounts of total value added inform of raw meat in hotels and restaurants exceed 20,080 Birr. This also indicates that the specific value chain actors added more than 100% value for the live cattle that marketed 9500 Birr in the district. The highest and lowest net return was obtained from bulls fed Taro based supplement and sugarcane based supplement, respectively. It was concluded that fattening bulls by using Taro as energy supplement is recommended for the areas where Taro is available and cheap. Market actors that sell raw meat overexploit profit margin belong to producers that need systematic government intervention for efficient benefit share. Introduction Borana beef cattle with appropriate feeding intervention is believed to optimize the economics gains of actors in beef value chain.

Fifty water samples including Surface water, Dug well, Hand pump and Bore well during pre-monsoon (May- June) and post-monsoon season (November) in parts of Mulugu-Venkatapur mandals, Warangal District to an extent of 453 Km2 and falls under Top sheet No. 56 N/15 and 56 N/16 of Survey of India were collected. The samples were analysed for major ion chemistry to study the groundwater characteristics and its suitability for drinking as well as irrigation purposes. The pH ranges from 6.7-8 indicating water is slighly acidic to alkaline in nature. TDS ranges from 201-3612 mg/l and 154-3457 mg/l during pre and post monsoon season. Total Hardness (TH) ranges from 100-1000 mg/l and 38.8-2148 mg/l; Chloride ranges from 7.81-1667 mg/l and 7.6-1089 mg/l; sulphate ranges from 2-1533 mg/l and 5.2-1200 mg/l during pre and post season respectively. Majority of the samples are suitable for domestic purposes due to low to medium hardness, however few samples described very hard and unsuitable for domestic, drinking and irrigation purposes. Various indices like Salinity Index, Sodium Absorption Ratio (SAR), Kelly’s Ratio (KR), Residual Sodium Carbonate (RSC), Soluble Sodium Percentage (SSP), Permeability Index (PI) and Water Quality Index (WQI) are used to classify groundwater and surface water for drinking as well as irrigation purposes. Besides this, Piper trilinear diagram, Wilcox diagram, Doneen’s classification and Gibb’s plot were studied for geochemical controls, and hydrogeochemistry of groundwater and surface water.

The water quality of rivers is an issue of serious concern today. Rivers are heavily impacted due to their use for carrying off the industrial, municipal, agricultural and domestic effluents. Water samples were collected for the present study from the Ganga River at Kanpur, Allahabad and Varanasi sites, during the period 2011-2012. The minimum temperature (17°C) was recorded in winter season. The pH, TDS, EC, sulphate, phosphate, nitrate, BOD and COD values exhibited their minimum at Allahabad site. The chloride and dissolved oxygen were recorded minimum at Kanpur site while alkalinity and total hardness had their lowest values at Varanasi site. The water quality of the Kanpur site was very poor compared to Varanasi and Allahabad sites. However, the Ganga river waters could host some tolerant fish species such as the exotic Cyprinus carpio and Oreochromis niloticus and also catfishes. All these species are very hardy, in respect of poor water quality, thus they (exotic species) have powerfully invaded in degraded systems worldwide.

Kivi Plainis located in the northeastern city of Kiviin Ardabil province. Due to the large number of villages in the desert and its people engaged in agriculture and animal husbandry, Study of ground water to determination of the optimal location of wells is important. In this regard, geoelectric technique was used for studies of groundwater quality and quantity of Kivi plain. In this research, the resolution of the subsurface layers, detection of saturated zone, determination of basement, detection of the general direction of groundwater and changes of resistivity in sounding points and profiles have been studied. The number of 196 vertical electrical sounding on nine profiles and the number of 9 sounding in variety points and in vicinity of exploratory wells by schlumberger array in the study area have been taken. "IPI2win" software is used for the interpretation of vertical electrical sounding curves and one-dimensional modeling. By “Res2dinv”, twodimensional modeling and preparation of resistivity section have been taken. According to the results of the interpretation of the data in the study area, sediments inparts of the Middle East and Northern have developed, and from the surface to the depth of alluvium and marl deposits were included. More aquifer layers in marly sand deposits, silt and sand, crushed limestone and salty zones were observed. Basement is included most of marl (with the layers of sandstone and conglomerate), limestone and silt. According to the basement, the topography slope of the area and isopiezecurves, groundwater movement is toward the northeast.

If adequate measures are not taken to protect the water bodies in Ghana, the rivers will dry up and those left will be highly polluted and the country will have to import drinking water from the neighbouring countries and from abroad for human consumption. Also, lots of lives and property would be lost through flooding in most cities in every rainy season if certain habits like building on water ways and dumping of rubbish into drains are not discouraged.

Mathematical modeling of systems requires a considerable knowledge about the subsystems, and the various rate processes and transfer coefficients that control the system. One such system involves changes in the carbon chemistry of the aquatic media during photosynthesis because inorganic carbon is a potentially limiting factor in the aquatic media. We used two artificial systems: an aquarium and a pond system with Hydrilla as the major photosynthetic organism to study the changes in the carbon chemistry and the carbon species taken up. The study depicts that carbon dioxide is the major molecular species taken up and in its absence; free carbon dioxide is released initially from the dissociation of bicarbonate ions rather than its direct use. The rate of entry cannot be accounted directly by diffusion alone because of the pH gradients in and out of the cell, and therefore carbon concentrating mechanisms and aquaporins  are thought to be involved in the process. The study gives a clear picture of the amount of carbon dioxide available in the free form and the amount released from bicarbonate ions and used in photosynthesis, and can be accounted perfectly.

Environmental/Ecological flow refers to the minimum flow of water to be maintained in a water body (river, lake, etc.) to sustain ecosystem services. Understanding environmental flow is important to ensure the local ecological and social (people, agriculture and horticulture, etc.) needs in a sustained and balanced way, while designing large scale projects (such as hydro-electric, river diversion, etc.). Western Ghats are the mountain ranges extending from southern tip of India (Tamil Nadu-Kanyakumari) to Gujarat. These mountain ranges are rich in biodiversity with diverse and endemic flora and fauna, and is birth place to numerous perennial rivers namely Netravathi, Sita, Sharavathi, Aghanashini, Krishna, Cauvery, etc. Western Ghats is often referred as water tower of peninsular India, due to the water and food security provided by the ecosystem through array of services. The region is also one among 35 global biodiversity hotspots. However, deforestation due to large scale land cover changes has affected the water sustenance in the region evident from the quantity and duration of water availability during post monsoon period. Forests in the Western Ghats along with the soil characteristics and precipitation plays a major role in storing water in sub-surface (vadoze and groundwater) zones during monsoon, and releases to the streams during post monsoon periods catering to the needs of the dependent biota including humans. Some of these undisturbed/ unaltered natural flow conditions in rivers and streams have proved their worth with the presence of rich and diverse species and array of ecosystem services, which also has helped in sustaining the livelihood of dependent populations. The undisturbed flow conditions guarantees the natural flow as well as minimum flow in streams to sustain the ecosystem services, which helps in meeting the social and ecological needs. Growing demand to cater the demands of burgeoning human population coupled with accelerated pace of deforestation due to unplanned and senseless developmental projects in the ecologically fragile regions have led the water scarcity even in regions receiving high amount of rainfall. In the current communication an attempt is made to understand the linkages between the hydrological dynamics across varied landscape with the anthropogenic and ecological water needs. If the available water resource meets the societal and environmental demands across seasons, the catchment is said to achieve the minimum flow requirements. The federal government has plans to divert the water from rivers in Western Ghats region to the dry arid regions in Karnataka. In this regard, environmental flow assessment of Yettinaholé river in Central Western Ghats is carried out to understand the feasibility of river diversion through the assessment of hydrologic regime with the analysis of land use dynamics (using remote sensing data), meteorological data (rainfall, temperature, etc. from IMD, Pune), hydrological data (from gauged streams) apart from field investigations in the catchment. The catchments receive annual rainfall of 3000-5000 mm (Department of Statistics, Government of Karnataka). Land use analyses reveal that Major portion of the catchment is covered with evergreen forest (45.08%) followed by agriculture plantations (29.05%) and grass lands (24.06%). Water yield in the catchment computed for each of sub-catchments based on the current land use and other related hydrological parameters using empirical method. The total runoff yield from the catchments is estimated to be 9.55 TMC. About 5.84 TMC is required for domestic purposes including agriculture, horticulture and livestock rearing. The quantum of water required to sustain fish life in the streams is about 2 TMC, computed based on hydrological discharge monitoring and fish diversity in streams during 18 months (covering all seasons) in select streams in Western Ghats. Considering the available water is sufficient only to meet the anthropogenic and ecological needs in the region, the sustainable option to meet the water requirements in dry arid regions would be through (i) decentralized water harvesting (through tanks, ponds, lakes, etc.), (ii) rejuvenation or restoration of existing lakes/ponds, (iii) reuse of waste water, (iv) recharging groundwater resources, (v) planting native species of grasses and tree species in the catchment (to enhance percolation of water in the catchment), (vi) implementation of soil and water conservation through micro-watershed approaches. Implementation of these location specific approaches in arid regions would cost much less compared to the river diversion projects, which if implemented would help the section of the society involved in decision making, construction and implementation of the project.

In urban areas, population growth generates significant amounts of wastewater that is treated in sewage treatment plants specialize or reject directly controlling interest in the natural environment. Many scientists are looking into the issue to try to find solutions to clean water and make it drinkable. We are interested in the technique of sand filtration (in the region southwest of Algeria), as an essential phase for the treatment of wastewater, such methods are known to be well suited to rural areas, since they have a good quality of treatment, a relatively simple operation and low maintenance. The method is based on the following principle: a slow filtration, water passes under a constant hydraulic load (30 cm water) the filter bed (60 cm of sand), the hydraulic load is kept constant during the experiment. A physicochemical analysis is performed on the water sample before and after filtration, the filter bed to give us a discount of around 50% in the levels of contaminant parameters such as NTK, Ammonium, Nitrate, and Nitrite. The reduction of BOD, COD and suspended solids is about 90%. It was observed a significant increase in the potassium from 33.19 mg/l to 99.89 mg/l.