There is comparatively limited information in the humid tropics on the surface and sub-surface permeability of: (i) forests which have been impacted by multi-decades of human occupancy and (ii) ...forestation of land in various states of degradation. Even less is known about the dominant stormflow pathways for these respective scenarios. We sampled field saturated hydraulic conductivity,
K
∗ at 23 sites at four depths (0
m,
n
=
166), (0.10
m,
n
=
139), 0.45–0.60
m,
n
=
117, (1.35–1.50
m,
n
=
117) under less disturbed forest (Forest), disturbed production forest of various local species (Degraded Forest) and tree-plantations (
Acacia auriculiformes, 7–10
years old,
Tectona grandis, ∼25–30
years old,
Casuarina equisetifolia, 12
years old) in the Uttar Kannada district, Karnataka, India, in the Western Ghats. The sampling strategy was also undertaken across three physiographic blocks and under three main soil types. Subsequently the determined
K
∗ were then linked with rainfall intensity–duration–frequency (IDF) characteristics to infer the dominant stormflow pathways.
The Degraded Forest shows an
order of magnitude decline in
K
∗ at the surface as result of human impacts at decadal to century time scales. The lowest surface permeability is associated with the Degraded Forests over the Laterite (
Eutric Nitosols and
Acrisols) and Red soils (
Eutric Nitosols) and infiltration-excess overland flow, IOF probably occurs. Further there is a progressive decline in
K
∗ with depth in these soils supporting Degraded Forests. The
A. auriculiformes plantations over the Red and Lateritic soils are progressively restoring the near-surface
K
∗, but their
K
∗ still remain
quite low when compared to the less disturbed forest permeability. Consequently these plantations still retain the ‘memory’ from the previous degraded state. In contrast the permeability of the Black soils (Vertisols) are relatively insensitive to
T. grandis plantations and this soil group has a very low
K
∗, irrespective of land cover, so that IOF likely prevails. Overall, the Laterites are the most variable in
K
∗ when compared to the other soil groups. Thus when compared to other studies, IOF is probably more prevalent in this region. More especially so, when taking into account the marked reduction in surface
K
∗ during the wet season when compared to dry season measurements. In addition, we have demonstrated the potential for the ‘infiltration – trade-off’ hypothesis to be realized in this landscape under certain conditions of land degradation and restoration. It is most relevant to the combination of degraded sites and
A. auriculiformes plantations on Red or Laterite soils using the less disturbed forests as the baseline. The intensity of forest use and effects of monoculture plantations on soil ecology (relative to native, mixed forests) is likely to be the critical factor in affecting surface
K
∗ over time. Predicted changes in the intensity of rain events in the future is likely to enhance overland flow on degraded sites on all soils and especially on Black soils, and restoration efforts by all stake-holders, preferably using native or non-invasive species, are needed to address this concern.
► Monitored soil moisture under natural forest, degraded forest and acacia. ► Analyzed spatial and temporal variations in weekly moisture contents. ► Mean soil moisture content was not significantly ...different between land covers. ► Developed and validated statistical soil moisture prediction models.
An understanding of the soil moisture variability is necessary to characterize the linkages between a region’s hydrology, ecology and physiography. In the changing land use scenario of Western Ghats, India, where deforestation along with extensive afforestation with exotic species is being undertaken, there is an urgent need to evaluate the impacts of these changes on regional hydrology. The objectives of the present study were: (a) to understand spatio-temporal variability of soil water potential and soil moisture content under different land covers in the humid tropical Western Ghats region and (b) to evaluate differences if any in spatial and temporal patterns of soil moisture content as influenced by nature of land cover. To this end, experimental watersheds located in the Western Ghats of Uttara Kannada District, Karnataka State, India, were established for monitoring of soil moisture. These watersheds possessed homogenous land covers of acacia plantation, natural forest and degraded forest. In addition to the measurements of hydro-meteorological parameters, soil matric potential measurements were made at four locations in each watershed at 50
cm, 100
cm and 150
cm depths at weekly time intervals during the period October 2004–December 2008.
Soil moisture contents derived from potential measurements collected were analyzed to characterize the spatial and temporal variations across the three land covers. The results of ANOVA (
p
<
0.01, LSD) test indicated that there was no significant change in the mean soil moisture across land covers. However, significant differences in soil moisture with depth were observed under forested watershed, whereas no such changes with depth were noticed under acacia and degraded land covers. Also, relationships between soil moisture at different depths were evaluated using correlation analysis and multiple linear regression models for prediction of soil moisture from climatic variables and antecedent moisture condition were developed and tested. A regression model relating near-surface soil moisture (50
cm) with profile soil moisture content was developed which may prove useful when surface soil moisture contents derived from satellite remote sensing are available. Overall results of this study indicate that while the nature of land cover has an influence on the spatio-temporal variability of soil moisture, other variables related to topography may have a more dominant effect.
With the increasing urbanization, agriculture, industrial activities along the coastal stretches of India, more and more people depend on ground water due to which there are cases of large scale ...decline in both quantity and quality. One of the State which is facing a critical change in its geomorphology and land use/land cover is Goa which is known for its tourism industry. Therefore, the water management will be a major issue in the years to come. A field survey conducted in parts of north Goa coast to understand the ground water availability status, quality issues and salinity conditions of ground water due to sea water intrusion. Accordingly, an attempt was made to understand the extent of seawater mixing with ground water using a model known as GALDIT Model. GALDIT is an indicator based model which assess and quantifies the significance of vulnerability to seawater intrusion due to excessive groundwater withdrawals. The system contains three significant parts: weights, ranges, and ratings. Each GALDIT factor has been evaluated with respect to the other to determine the relative importance of each factor. Accordingly indices were calculated for the selected wells (wells were selected along the coast and also perpendicular to the coast). Results obtained by GALDIT model showed that about 42% of the wells in the study area are low vulnerable and 58% of the wells are moderately vulnerable to sea water intrusion.
Ghataprabha is an auxiliary of river Krishna and flows over Chandgad taluk of Kolhapur district, Maharashtra. Bauxite mining was one of the major issues in this part of the sub-basin, in the early’ ...90s due to which there was a strong public protest about the quality of water. Accordingly, a survey was conducted to get the public perception on water pollution in the headwater catchment of Ghataprabha sub-basin. During the survey, a broad opinion was expressed with regard to water quality contamination of Ghataprabha river by a section of the society living in the riparian zones of the river basin. Therefore, in this paper, an effort has been done to understand the in variation in water quality with special reference to groundwater. Thirty-eight groundwater samples (nineteen each from before and after rainy season) were assembled and analysed for EC, TDS, pH, chlorine ion HCO
3
, SO
4
, PO
4
, Ca, Mg, Na and K. The values have shown that the density of all measured factors is broadly within the permissible limits (as per BIS Standards), before and after-monsoon. The present observations do compared with the earlier reported parameters of the year 2000. The results show that there is a betterment of water quality in the mining field as compared to previous data. This clearly demonstrates that the mining area can be reclaimed over the years by taking appropriate conservation measures. However, ionic ratios such as SAR, KR and SSP showed considerable variations indicating that there is localised impact on water quality resulting in the groundwater pollution. DRASTIC indices were computed based on hydrogeological characteristics and found that more than 30% of the observatory wells are contaminated where the nitrates are very high (more than 45mg/L) which clearly demonstrated that groundwater is getting polluted in high intense agriculture areas and also in areas close to settlements.
Infiltration is one of the most important hydrological process through which water enters the soil surface and plays a significant role in controlling soil water storage, crop yields, irrigation ...efficiency and solute entry into the soil profile. In agriculture fields, generally, the top soils are enriched with high organic matter and clay, particularly in black soils that promotes sorption, biological degradation and transformation of contaminants. During the process some of the chemicals applied to farm land, move down with the deep percolating water from the root zone and there are likely chances to pollute the underlying ground water. Such instances are reported by locals in areas dominated by black soils of Malaprabha command area. In order to understand the extent of groundwater contamination through chemical fertilizers, insecticides and manures, two agricultural plots (sugarcane and banana plantation) have been identified in parts of Malaprabha command area covering parts of Saundatti, Ramdurg (Belagavi district) and Nargund taluks (Gadag district). Hydraulic properties such as infiltration and hydraulic conductivity were determined in the field. Soil samples were collected and analysed in the laboratory for texture and porosity. The study indicated that the soils of the region are layered in structure. Further, it is noticed that the coarse textured loamy soil is present below the fine textured soils (such as silty loam or clayey loam). Due to the presence of fine soils at the top, the irrigated water get accumulated and the evaporation takes place relatively faster and results in the accumulation of excess salt. It is also noticed that the layered soils have obvious effects on solute transport and salt accumulation in the clay rich soil layer at the interface. The average salt accumulation (Total Nitrogen) observed in the study area within soil profile is 18.7g/kg. The maximum salt accumulation (21.38 g/kg) occurred in the top layer of sugarcane plots followed by banana plantation (19.85 g/kg). It is also noticed that there are remarkable changes in the interlayered soils with reference to water infiltration characteristics and salt leaching intensities. Study revealed the fact that the properties of the soil profile with a silty loam interlayer is better than with a silty clay loam interlayer.
Belgaum city is a developmental hub of Karnataka State in India. In the recent time, the Government of Karnataka has planned to set up many processing industries in the vicinity of Belgaum to meet ...the growing needs of the region and to ease out the pressure on the already existing industrial hubs in Karnataka State. Ghataprabha, a tributary of river Krishna, is one of the major sources of water supply to Belgaum city and adjoining areas. During the last decade, a lot of anthropogenic activities such as unplanned agricultural activities are ongoing in many parts of the catchment. Therefore, people of Belgaum are more concerned about the quality of water in Ghataprabha river. Considering the significance of water quality of the river, surface water samples were collected during Pre- and Post-monsoon season from selected locations and analyzed for both physical and chemical constituents in the laboratory. The results indicate that the chemical parameters such as bicarbonates, sulphates, chlorides, sodium, potassium, calcium and magnesium are within the permissible limits. QUAL2E model was applied to assess the impact of point and non-point sources of pollution on the river water quality. Results show that the water quality conditions are highly acceptable all along the river stretch. Further, the variation of DO–BOD
5
with river discharge was also estimated. Also, a significant variations in DO (decrease in DO) with the increase in river flow was observed. However, at the downstream end, considerable improvement in DO was noticed which is attributed to the damming effect of the reservoir.
We review the current status of experimental studies in India to understand the linkages between afforestation and hydrology. This discipline deals with the use and management of water, social ...awareness of environmental problems, and ecosystem limitations on provision of watershed services by river basins in the mountain regions of India. Our review begins with examination of experimental works in tropical countries and proceeds to discussion of initiatives of Indian research institutes and Government organizations towards establishing experimental watersheds to understand the impacts of land cover changes on hydrologic regimes in the Indian sub-continent. This is followed by the review of the experimental work carried out by various authors to assess the impact of land cover changes on major water balance components such as, runoff, groundwater, evapotranspiration and sediment yield. The spatial scales of these experiments have been limited to small watersheds or field plots. This paper also describes impacts of human interventions (such as plantations of exotic forest species to restore degraded landscapes) on the water balance components in diverse hydro-geo-environmental conditions in the Indian sub-continent. We focus on identifying the research areas which require immediate attention to develop tools to assist planners and policy makers in assessing and managing the water resources in these complex environments. The review is largely based on research results reported during the last 20 to 30 years.
Tungabhadra River is the chief source for drinking water and agriculture developments in Davangere and adjoining districts of Karnataka. It is reported that the water of Tungabhadra is getting ...polluted by the direct / indirect effluent discharges due to which people living on the river bank are facing the problem of drinking water. River Bank Filtration (RBF) wells which will naturally treat the polluted surface and ground water have been drilled in perpendicular to the river at a distance of 30m, 50m and 80m to understand the extent of treatment of RBF wells to provide clean and safe drinking water. The present study deals with the problems of water quality in a selected village (Somlapura) located in a hard rock terrain of river Tungabhadra, Karnataka, India. As a part of the investigation, water samples were collected from River Bank Filtration wells and adjoining river and aquifers were analyzed using standard methods. Outcomes of water quality presents that the concentrations of turbidity and total coliform were lesser in the RBF well water samples when compared to Tungabhadra River water samples. The water from RBF wells contained fresh water, which is highly mineralized and free from bacterial contamination relative to the water from river. However, groundwater of the adjoining aquifers showed wide variations in various physio-chemical parameters. From the analysis, unsafe levels of total coliforms (included E.coli and F. Coli) were detected in Tungabhadra River i.e., It varied between 1680 and 3179 MPN/100 ml. It is observed that the average removal efficiency of coliform bacteria from RBF well 1 & 2 was 99.84% and 99.82% respectively.
The objective of this study is to apply and test a simple parametric water balance model for prediction of soil moisture regime in the presence of vegetation. The intention was to evaluate the ...differences in model parameterization and performance when applied to small watersheds under three different types of land covers (
Acacia
, degraded forest and natural forest). The watersheds selected for this purpose are located in the sub-humid climate within the Western Ghats, Karnataka, India. Model calibration and validation were performed using a dataset comprising depth-averaged soil moisture content measurements made at weekly time steps from October 2004 to December 2008. In addition to this, a sensitivity analysis was carried out with respect to the water-holding capacity of the soils with the aim of explaining the suitability and adaptation of exotic vegetation types under the prevailing climatic conditions. Results indicated reasonably good performance of the model in simulating the pattern and magnitude of weekly average soil moisture content in 150 cm deep soil layer under all three land covers. This study demonstrates that a simple, robust and parametrically parsimonious model is capable of simulating the temporal dynamics of soil moisture content under distinctly different land covers. Also, results of sensitivity analysis revealed that exotic plant species such as
Acacia
have adapted themselves effectively to the local climate.
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