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Authors: Dubey, Om Prakash
Issue Date: 2003
Abstract: On the southern foot of the Himalayas, lies a very prominent east west running geomorphic feature, commonly known as Piedmont. Sediments in this zone range from boulders to sand, silt with little clays. The rugged topography, fragile ecological set up, gravelly soil has discouraged human settlements in this terrain which has poor connectivity to the neighboring areas. Nevertheless, with increase in population this region has attracted the local populace for their needs of food, fodder and fire wood. Accordingly the area is being used, wherever inhabited,without proper planning in unscientific manner. Therefore,there is a need to evaluate this geomorphic unit for better use of this land in environment friendly way. Thus a part of the piedmont lying between rivers the Ganga and the Yamuna covering an area of about 2000 km sq. has been taken up for investigation as a model study of development of these areas for agricultural land use. Preliminary field investigations indicated that the land use in the area is influenced by the land elevation, land slope, drainage, rainfall, temperature, soil type, erosion, surface and groundwater. In this study these parameters have been evaluated through synergistic use of remotely sensed data, field investigations, laboratory studies and analysis of existing data. GEOMORPHIC FEATURES Based on satellite images, IRS _ LISS II, False Colored Composite (FCC), and Topographic Maps at 1:250,000 and 1:50000 scales along with field surveys the area was classified in to four major geomorphic units, namely, the northern most, Upper Regime Piedmont (UP), Middle Regime Piedmont (MP), to the south the Inter Channel Plainer Area (IC), and Channel Braid Bars(CB). The northern most geomorphic unit (UP) which is in direct contact with the exposed Himalayan hill slope is characterized by undulating topography, with average elevation more than 350 mabove mean sea level (m s 1) and ground slope of more than 3° (5.3%). South of UP geomorphic unit, where ground elevation ranges between 300 m and 350m above ms 1, ground slope between 2° (3.5%) and 3° (5.3%) has been designated as MP geomorphic unit. The southern most unit that is characterized by near flat, non undulated topography, slope less than 2° (3.5%), ground elevation between 250 mand 300 mabove msl has been designated as Inter Channel Plainer Area (IC) unit. The fourth unit is designated as Channel Braid Bars (CB). The geographical area of UP, MP, IC, and CB geomorphic units are about 17.4%, 12.6%, 63.4% and 6.6% of the total (about 2000 sq. km) area. The Inter Channel Plainer Area (IC) unit is further subdivided in to three subunits namely: (i): l\\ characterized by frequent flooding; (ii): I2: experiences occasional flooding; and, (iii): I3: is relatively free from flooding Geographical areas of these subunits are 19.6%, 14.4%, and 29.4% totaling to 63.4% of the total study area (about 2000 sq km) SOIL CHARACTERISTICS In order to assess the soil characteristics of the area, 250 soil samples collected from various geomorphic units, were analyzed to determine the soil texture , mineralogical composition , salinity , alkalinity , hydraulic conductivity and hydrologic soil classification. Field investigations indicate that the UP geomorphic unit is characterized mainly by coarse gravely sediments _ gravels (boulders, cobbles, pebbles, granules), and coarse sand. The MP geomorphic unit contains mainly gravely sands _ finer gravels with occasional cobbles, pebbles, granules, rich in coarse grained to medium grained sand, silts and clays. Grain size analysis of sandy components of the UP geomorphic units 11 indicates that d50 of the component which is about 50 cm thick is more than 1.0 mm. The sandy component of the MP soil is about 15cm to25 cm thick and d50 is 1.0 mm to 0.5 mm. The soils in the IC geomorphic unit is characterized by relatively finer sediments, mainly sand, silt and clays, d50 of the soil is less than 0.025 mm. Soil thickness is more than 25 cm. d5o of soils in the channel braid bars (CB) is varying between 1.0 mm and 0.025 mm. Petrographic investigations, indicate that the boulders, cobbles, pebbles and sand are of heterogeneous nature with various types of rocks mainly quartzite with small amount of sand stone, phyllites and limestone. The sand and silt are made up of mainly quartz with mica and feldspar. X - Ray investigations indicate that the clay minerals are mainly Kaolinite, Illite with some Vermicullite and montmorillonite. From mineralogical considerations the soils can support a variety of crops. Electrical conductivity of the soil samples indicates that, the electrical conductivity of the UP geomorphic unit soils is about 0.04 dsm"1, in the MP geomorphic unit it is 0.20 dsm" and in IC unit it is 0.25 dsm"1. The PH value of the soils in the UP is 7.8, in the MP it is 7.7 and in the IC unit it is 7.1. These values indicate that electrical conductivity is showing an increasing trend from north to south, whereas, PH is showing a reverse trend as it is decreasing from north towards south. Spatial variation of electrical conductivity and PH indicate that the soil in the area is neither salinenor alkaline. Hydraulic conductivity of the soil samples determined by falling head method indicates that in the UP geomorphic unit it is 80 cm/hr while in the MP geomorphic unit it is 70 cm/hr and in the IC geomorphic unit it is 20 cm/hr. Field measurement of infiltration capacity indicates that in the UP geomorphic unit it is 16 cm/hr. In the MP geomorphic unit it is 12 cm/hr and in the IC geomorphic unit it is 2 cm/hr. From the spatial variation of hydraulic conductivity and infiltration capacity it is inferred that both hydraulic conductivity and infiltration capacity is showing an increasing trend from north towards south. From soil investigations it is inferred that soils in the north are coarse grained, in highly permeable and highly aerated as compared to the soils in south. Further soils in the north are difficult to work with. Such a soil can support a variety of crops. WATER RESOURCES The area is bounded by two perennial rivers the Ganga and the Yamuna. In between these two rivers, the area is traversed by a number of seasonal streams namely, Hindon, Solani and Ratmau etc, which forms the tributaries of these two rivers. Besides these the area has three canal systems, namely, Upper Ganga Canal, Eastern Yamuna Canal and Khara Canal. Except in the area close to canals and streams groundwater is the major source of water. Groundwater Resources Based on the ground water level measured during the period 1984 -2001 it is found that in the UP geomorphic unit the depth of the groundwatertable is about 33m below ground level (bgl) and fluctuation in this unit is about 2.8 m bgl. In the MP geomorphic unit it is about 20 m bgl and fluctuation is about 2.0 m. In the IC unit the depth of the water table is about 5 m bgl and fluctuation is about 1.5. The chemical analysis of water indicates that it is fresh and useable for domestic and agricultural purposes. The groundwater resource in the area was estimated using Groundwater Estimation Committee (GEC, 1997, Govt, of India) norms. The study indicated that the major source of the groundwater in the area is rainfall recharge; canal seepage and irrigation return flow. About 85% of the rainfall occurs during June and September. On annual basis rainfall recharge in the area is about 33%, whereas GEC recommended norm is 20% to 25% and computed by empirical relation is about 10%. Hence, empirical formula (Chaturvedi, 1947) was modified as : Rr = a(R-b)05 IV Where Rr is rainfall recharge, R is rainfall, and a&b are constants. The numerical values of these constants were determined in least square sense. Based on 1984 -1995 data, numerical value of the constants was worked out to be 4.0 for UP and MP geomorphic unit; it is 3.3 for sub geomorphic units I, &L; whereas for sub geomorphic units U & CB it was found to be 3.2. The numerical value of the constants b was worked out to be 25 for UP geomorphic unit, 30 for MP geomorphic unit, 35 for h & I2 geomorphic sub unit, 38 for I3 and CB geomorphic sub unit. After this modification efficiency ofthe prediction was found to be about 82% In order to determine the period when the rainfall recharge is available for pumping, cross correlation studies between rainfall and depth of groundwater table were carried out. It is observed that the coefficient of correlation is showing an increasing trend with time and after achieving a maximum value it starts decreasing. In the UP geomorphic unit, rainfall takes minimum time (10-20 days) to recharge the groundwater. Inthe MP geomorphic unit it is 20 days, whereas in the IC geomorphic unit it takes about 40 to 50 days to recharge the groundwater. Such studies have further indicated that in the UP and MP geomorphic unit the recharged water is available for about 20 to 40 days, whereas in the IC geomorphic unit it is available for longer duration, about 8 months in the shallow regimes. It was found that, in spatial domain, the rainfall recharge is influenced by land cover in addition to amount of rainfall. Hence, a simple model, G = AP, where G is a column vector as rainfall recharges perunit rainfall; Ais land cover system operator matrix and P is the rate of rainfall recharge. Land cover input to the model was determined from analysis of IRS LISS II; FCC .The model was calibrated and tested. Model efficiency was found to be about 85%. Surface Water Resources Surface water resources were estimated using the Soil Conservation Society (SCS) model. The model was found to yield values of stream flow which is about 35% higher than the observed values. Thus, the SCS model was modified for this area and is presented below. Q= (P-0.3S)2/P + 0.7S; Where Q is stream flow in mm, P is rainfall in mm, and S is defined by following relation. S - (25400/CN) - 254 Where, CN is popularly known as Curve Number, a constant which depends upon land cover soil complex of the area. In the study the numerical value of the curve number, CN, for different land cover _ soil complex was determined in the Least Square Sense. After these modifications the model was found to be yield results with in ± 15% error. Keeping in view the fact that the piedmont area is poorly monitored and studied for the estimation of stream flow a simple model using only two parameter, namely the rainfall and land cover was developed. The model is, q = AC, where q is stream flow vector per unit rainfall, A is land cover system operator matrix and C is run off coefficient vector for different land cover. System operator matrix, A, was extracted from the analysis of IRS LISS II, FCC. The model was calibrated and tested. The efficacy of this model was found that the model yields results with in ± 15 %. Available Water Resources As mentioned earlier except rivers Ganga and Yamuna streams are flashy in nature. Field investigations indicated that stream flow in the flashy river is available for short duration, less than a day or two and hence the direct use of stream flow for agricultural purposes is VI very limited. Further groundwater is the only dependable source of water for irrigation. The study indicated that on an average about 270 x 10 ha mrecharged water is available annually. Water availability in the UP and MP geomorphic unit is much lower as compared to the IC geomorphic unit. Further conjunctive use ofsurface and groundwater is essential for growing a variety of crops. OPTIMAL LAND USE In the area more than 80% of the land is used for agricultural use. Field surveys indicate that wheat, sugarcane, paddy, maize and masoor are the main crops grown in the area. At existing land use, total food production (288270 T/year) is found to be more than the local demand (147278 T/year);whereas the total fodder production is (1472072 T/year) is less than the local demand (1500000 T/year). The total fire wood production is (52781 T/year) which is less than the demand(91250 T/year). Thus, the total food grain production is not only sufficient for the local demand but is a source of income. On the other hand the fodder and fire wood production is less than the local demand, thereby leading to encroachment over forest land resulting into continual environmental degradation. Thus, there is a need for optimal use of land aiming at fulfilling the local needs of food grain, fodder, fire wood and improving economic conditions along with maintaining the environmental balance. In view of above Linear Programming (LP) approach was made to allocate land for different uses. Input to the LP model was determined through field surveys and investigations of different geomorphic features. Based on this approach the food grain production can be increased to four times. The current deficit in fodder and fuel wood production can be made over. This will help in improving the economic condition of the villagers and maintaining the environmental balance vn Crop Suitability Vis-a-vis Geomorphic Unit With a view to develop a simple methodology for crop suitability assessment detailed field investigations were carried out. It was found that crop yield varies from one geomorphic unit to another. To study the spatial variation in crop yield, concept of Bench Mark Unit - a unit having highest yield of a particular crop, and a Productivity Index (PI) - ratio of crop field from an investigation area to the Bench Mark Land Unit was introduced. It was found that the PI for the area is low (0.46 to 0.82). PI for UP and MP geomorphic units are low as compared to IC geomorphic units. PI for maize, groundnut and urd crop is relatively higher (0.76) in the UP and MP geomorphic units. PI for wheat, sugarcane and paddy is higher (0.70) in the Ii and h subunits. For all the crops in the I3 subunits, PI remains more or less close to 0.60 to 0.68. In the CB units, PI is lowest (0.46 to 0.56) for each crop and may come down to zero if affected by flood erosion. Correlation study between terrain parameters and PI indicate that terrain parameters are highly related (coefficient of correlation, p = 0.87 to 1.00). Land slope is negatively related with soil thickness (p = -0.87). It is directly related with soil texture, d50 (p = 0.997. It is is directly related with depth of groundwater table (p = 0.992). It is inversely related with productivity index (p = -0.958). This indicates that terrain characteristics control the intensity of agriculture. Each geomorphic unit has its own terrain characteristics. The impact of simultaneous affect of terrain characteristics on crop yield has been assessed through multivariate approach - the Principle Component Analysis (PCA). PCA indicated that the first largest eigen value is 4.79.The second largest eigen value is 0.2 and other eigen values are negligible and hence ignored. The first principal component corresponding to the largest eigen value which accounts for about 99 % variation in the data is heavily loaded (0.961 to 0.992). In view of multivariate relationship of Productivity Index (PI) with terrain characteristics, namely, land slope (Ls), soil thickness (St), grain size (d5o), depth of the groundwater table (dw) taking in to account the first principal component has been worked out as: PI - 0.6213 - 0.000979 Ls + .000961 St - .000985 d50 - .0000992 dw This relationship can be utilized to assess the crop PI, for various geomorphic units which may help in use of a giventerrain for a crop. Use of land for various crops vis _ a _ vis geomorphic units has been presented in the form ofa map. It is inferred that the northern geomorphic units, namely, the upper and middle regime piedmonts are more suitable for maize, groundnut and urd (a variety of pulse) crops. However, wheat, sugarcane and paddy are the most suitable crops in the plainer areas, namely, Land I2 which are close to streams. In the geomorphic units I3 and the channel braid bars (CB), any crop can be grown but with risk ofcrop damage due to stream erosion especially during rainy season. It is expected that ifpiedmont land is used as suggested above it will enhance the food production by four times and make up the fodder and fire wood demand, which will help in improving the economic condition of the populace and development in environmental friendly way.
Appears in Collections:DOCTORAL THESES (Earth Sci.)

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