Chapter – 5 Hydrology and Water Assessment
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Chapter – 5 Hydrology and Water Assessment 5.0 General The proposed Wainganga (Gosikhurd) - Nalganga (Purna Tapi) intra-state link project of Maharashtra envisages diversion of 1772 Mm3 from the existing Gosikhurd (Indira Sagar) project (first National Project in the country) on Wainganga river in Pranhita sub-basin of Godavari basin for extending irrigation, domestic and industrial water supply benefits in six districts of Vidarbha region of Maharashtra State viz., Nagpur, Wardha, Amravati, Yeotmal, Akola and Buldhana before out falling into Nalganga project on Nalganga river of Tapi basin. Seasonal climate prevails in the link project area. Four distinct seasons are noticeable in the year viz., Monsoon from June to October, Post-monsoon from October to mid December, Winter from mid December to February and Summer from March to May. The climate is normally cold from December to February which is followed by hot season from March to May. The hydrology and water availability studies of the project are based on the Rainfall-Runoff relationships developed for four sub-catchments within the catchment of Wainganga at Gosikhurd dam site. 5.1 General Information about Regions (a) Wainganga/Pranhita Sub-basin of Godavari Basin The salient features/general information of the four sub-catchments upto Gosikhurd dam site in Wainganga sub-basin viz. Pench, Kanhan, Bagh and Wainganga is described as under: (i) Pench Sub-catchment The Pench is a tributary of the Kanhan River. It originates in the Chhindwara district of Madhya Pradesh and flows for about 200 km in the district and then for 56 km through Nagpur district of Maharashtra before joining Kanhan river. The catchment area of the sub-catchment is about 4847 km2. The climate of the sub-catchment area is usually pleasant most of the year, except in summer. The sub-catchment lies in the medium rainfall zone. Most of the rainfall is received during the South-West monsoon from June to October. About 10 rain Detailed Project Report of Wainganga (Gosikhurd)-Nalganga (Purna Tapi) link project gauge stations are located in and around the sub-catchment. The maximum annual normal rainfall of 1563 mm is recorded at Tamia rain gauge station, while the minimum of 980 mm is recorded at Mokhed rain gauge station. Chhindwara IMD observatory is located within the sub-catchment. As per the climatological data of the station for the period from 1981-2010, the normal daily maximum and minimum temperatures are found to be 39.2oC and 8.7oC in the months of May and December respectively. The normal maximum and minimum relative humidity are observed to be 88% and 33% in the months of August and April respectively. The normal maximum and minimum wind velocities are 7.9 km/hr in July/August and 3.1 km/hr in December. The normal maximum cloud cover is 6.7 oktas during the months of July/August, where as the normal minimum cloud cover is 1.1 oktas during the month of December. (ii) Kanhan Sub-catchment The Kanhan is Wainganga's longest tributary draining a large area lying south of Satpura range in central India. It rises in the southern spurs of the Satpura Range in the north-western region of Chhindwara District in Madhya Pradesh. Along its 275 km run through the Indian States of Madhya Pradesh & Maharashtra, it receives its largest tributary - Pench River, a major water source for the metropolis of Nagpur. The catchment area of the sub-catchment is about 7968 km2. The climate of the sub-catchment area is usually pleasant most of the year, except in summer. The sub-basin lies in the medium rainfall zone. Most of the rainfall is received during the South-West monsoon from June to October. About 9 rain gauge stations are located in and around the sub-catchment. The maximum annual normal rainfall of 1128 mm is recorded at Umred rain gauge station, while the minimum of 933 mm is recorded at Katol rain gauge station. Nagpur IMD observatory is located within the sub-catchment, while Betul IMD is situated just outside of it. As per the climatological data of both these stations for the period from 1981-2010, the normal daily maximum and minimum temperatures are found to be 42.7o C and 10.2o C in the months of May and December respectively. The normal maximum and minimum relative humidity are observed to be 93% and 19% in the months of August and April respectively. 133 Chapter – 5 Hydrology and Water Assessment The normal maximum and minimum wind velocities are 8.5 km/hr in June and 2.3 km/hr in October/December. The normal maximum cloud cover is 7.1 oktas during the month of August, where as the normal minimum cloud cover is 1.2 oktas during the month of April. (iii) Bagh Sub-catchment The Bagh is a major left bank tributary of river Wainganga. It originates from Chichgarh plateau in Gondia district of Maharashtra and flows north on granitic landscape. The river joins Wainganga near village Birsola in Balaghat district. The catchment area of the sub-catchment is about 5986 km2. The climate of the sub-catchment area is usually pleasant most of the year, except in summer. The sub-basin lies in the medium rainfall zone. Most of the rainfall is received during the South-West monsoon from June to October. About 6 rain gauge stations are located in and around the sub-catchment. The maximum annual normal rainfall of 1594 mm is recorded at Balaghat rain gauge station, while the minimum of 1004 mm is recorded at Khairbanda rain gauge station. Gondia IMD observatory is located within the sub-catchment. As per the climatological data of the station for the period from 1981-2010, the normal daily maximum and minimum temperature are found to be 42.3o C and 12.6o C in the months of May and December respectively. The normal maximum and minimum relative humidity are observed to be 85% and 25% in the months of August and April/May respectively. The normal maximum and minimum wind velocities are 5.7 km/hr in June and 1.9 km/hr in December. The normal maximum cloud cover is 5.3 oktas during the month of August, where as the normal minimum cloud cover is 0.6 oktas during the month of April. (iv) Wainganga Sub-catchment The catchment area of the sub-catchment is about 16061 km2. The climate of the sub-catchment area is usually pleasant most of the year, except in summer. The sub-basin lies in the medium rainfall zone. Most of the rainfall is received during the South-West monsoon from June to October. About 10 rain gauge stations are located in and around the sub-catchment. The maximum annual normal rainfall of 1404 mm is recorded at Mandla rain gauge station in the 134 Detailed Project Report of Wainganga (Gosikhurd)-Nalganga (Purna Tapi) link project catchment, while the minimum of 1076 mm is recorded at Lakhandaun rain gauge station. While Seoni IMD observatory is situated within the sub-catchment, Mandla and Chandrapur IMD observatories are located close to it. As per the climatological data of these IMD stations for the period from 1981-2010, the normal daily maximum and minimum temperature are found to be 42.9o C and 8o C in the months of May and December respectively. The normal maximum and minimum relative humidity are observed to be 87% and 22% in the months of August and April respectively. The normal maximum and minimum wind velocities are 13.1 km/hr in June and 2.4 km/hr in November/January. The normal maximum cloud cover is 6.7 oktas during the months of July/August, where as the normal minimum cloud cover is 1.1 oktas during the months of February/November/December. While the sub-catchment wise general information is described as above, the climate of the Wainganga/Pranhita sub-basin as a whole is presented as under: The climate of the sub-basin area is usually pleasant most of the year, except in summer. The sub-basin lies in the medium rainfall zone and is situated between the 900 mm and 1600 mm Isohyets. Most of the rainfall is received during the South-West monsoon from June to October. The maximum annual normal rainfall of 1594 mm is recorded at Balaghat rain gauge station in the catchment, while the minimum of 933 mm is recorded at Katol rain gauge station. The average annual normal rainfall for the sub-basin is 1193 mm. There are four IMD observatories located within the sub-basin viz., at Seoni, Chhindwara, Gondia and Nagpur. Three more observatories at Mandla, Chandrapur and Betul are located close to the sub-basin. As per the climatological data of these IMD stations for the period from 1981-2010, the normal daily maximum and minimum temperature are found to be 42.9o C and 8o C in the months of May and December respectively. The normal maximum and minimum relative humidity are observed to be 93% and 19% in the months of August and April respectively. The normal maximum and minimum wind velocities are 13.1 km/hr in June and 1.9 km/hr in December. The normal maximum cloud cover is 7.1 oktas during the month of August, where as the normal minimum cloud cover is 0.6 oktas during the month of April. The normal values of various 135 Chapter – 5 Hydrology and Water Assessment meteorological parameters of the IMD stations in Pranhita sub-basin are presented in Annexures 5.1.1 to 5.1.4.