Draft EIA Report of the Sunsari River Irrigation Project Existing Environmental Conditions CHAPTER EXISTING ENVIRONMENTAL CONDITIONS 3. EXISTING ENVIRONMENTAL CONDITIONS This chapter documents existing environmental conditions, particularly in the areas of physical, biological, socio-economic and cultural resources in relation to the Project activities. 3.1. Physical Environment 3.1.1. Topography and Climate The Sunsari River Irrigation Project (SRIP) area is located in the south-western part of the Sunsari District located between 26°24′N to 26°30′N in latitude and 87°04′E to 87°12′E in longitude. The elevation ranges from 64 meters to 80 meters above the mean sea level. The study area is rectangular in shape with E-W width varying from 4 to 8 kilometres and N-S length of about 22 kilometres. The western and southern part of the project area is bordered with India. The Project area is located at the eastern bank of the Sapta Koshi River. The terrain starts from foothills of the Siwalik range and slopes gently down to south with an inclination of 5 degrees on an average and is formed by alluvium of old and present rivers. The Project area is dominated by sandy soils having low to moderate water holding capacity. The climate in the project area is sub-tropical. Temperatures are high between March and October, the hottest month being the April, during which the mean daily maximum temperature is about 340C. During the cool period from November to February, mean monthly temperatures are in the range of 16 to 220C. The annual average rainfall between 1970 and 1993 was 1,867mm, raining intensively in the monsoon period, from late May to September. Long-term patterns of annual rainfall from 1973 to 2001 for Dharan Bazar and Chatra stations, and for Tarahara and Biratnagar Airport are given in the figure (Figure 3-1). No significant difference is observed amongst the available stations. The figures indicate that the rainfall fluctuates almost in 7 to 8 years term. In addition, rainfall at Biratnagar airport is noticeably high in 1974 and low in 1994. 4,000 Dharan Bazar Chatra 3,000 2,000 1,000 0 Tarahara Birtnagar 4,000 1973 1978 1983 1988 1993 1998 3,000 2,000 Figure 5.1.2 Annual Rainfall at Dharan B. and Chatra from 1973 to 2001 1,000 0 1973 1978 1983 1988 1993 1998 Figure 3-1 : Annual Rainfall from 1973 to 2001 3-1 Draft EIA Report of the Sunsari River Irrigation Project Existing Environmental Conditions Mean annual rainfall and monthly rainfall are summarized as follows (Table 3-1). Annual rainfall ranges from 1900 mm to 2400 mm and increases northward. Monthly distribution of rainfall is almost same among the stations with about 80 percent rainfall occurring in the monsoon season. However, correlative coefficient of daily rainfall among stations is about 0.6 only. Table 3-1 : Mean Annual and Monthly Rainfall Station Jan. Feb. Mar. Apr. May June July Aug. Sep. Oct. Nov. Dec. Total Dharan Bazar 13 15 24 61 173 374 631 572 408 143 15 7 2441 Chatra 17 14 24 58 161 394 603 474 353 143 17 7 2265 Tarahara 14 13 18 62 163 323 525 380 300 102 14 11 1925 Biratnagar 10 13 15 52 165 323 526 375 313 108 10 7 1917 Source: Climatological Records (different years) 3.1.2. Hydrology and Drainage System The prospective water resources for the project area are; 1) Sunsari River, 2) groundwater either shallow or deep, 3) water release from SMIP if extra water available is in the Chatra main canal, and 4) other rivers such as Budhi and its tributaries. The last one, Budhi River, provides already a diversion weir at a place named Kathale Nadi and Budhi Khola merge into the main Budhi River. The diversion weir commands about 1,800 ha of the area near the international border. Therefore, the downstream from the weir has no possibility that further water exploitation could be made. Though Kathale Nadi demarcating upstream eastern boundary of the project area seems an option to develop, the runoff is very little as suggested by the catchment area of only 20 km2. Also, a diversion in the Kathale Nadi will reduce the water release to the already functioning weir of the Budhi River. Therefore, the potential of the Sunsari River as the first development priority source and the groundwater as the supplemental water source together with the possibility of getting water from SMIP for the project area. There are two main rivers flowing through the study area in a direction parallel to the Sapta Koshi River. The Sunsari River – the source river for the irrigation project – flows southwest through the central part of the study area and the Budhi River flows towards the south along the eastern border of the study area. Mariya Dhar, abandoned course of the Sunsari River, is in the central part of the study area between Jalpapur and Kaptanganj. Sunsari River has a catchment area of 300 km2 at the prospective headwork site which is 600 m downstream from the E-W highway crossing point. This River originates in the Siwalik Range that is located in the northern part of Sunsari district. The river flows from the north to south and is meandering. The upper stream of the Sunsari River after confluence of Belaha Khola and Thalaha Khola is called the Sunsari River. As to the tributaries of the Sunsari River, there are two major ones; Kakar (Sardu) and Kuruwa (Seuti) Kholas. These rivers also originate in the Siwaliks. Kakar Khola flows along the right edge of alluvial fan in Dharan to the southeast and passes through the Terai plain. This tributary joins the Sunsari River at about 35 km from the top of Dharan alluvial fan. Kuruwa Khola flows along the left edge of Dharan alluvial fan to the south. It joins the Sunsari River at about 36 km from the top of Dharan alluvial fan. 3.1.3. Geology and Geomorphology The project area is the northern part of the Indo-Gangetic plain. Tectonically/geologically, the surrounding areas of the project can be divided into four zones: the Alluvial Formation, Siwalik Group, Takure Formation and Seti Formation. The Alluvial Formation un-conformably overlies the Siwalik Group. Siwalik Group contacts in fault with Takure Formation. Also, Takure Formation contacts in fault with Seti Formation. Table 3-2 summarizes the stratigraphic classification and outline of the general geology around the Study area: 3-2 Draft EIA Report of the Sunsari River Irrigation Project Existing Environmental Conditions Table 3-2 : The Stratgraphic Classification of the Study Area Quaternary Alluvium Boulder, Gravel, sand and Silt-Clay The Study Area, Bhabar (Recent) Zone (Alluvial Fan) Mid-Miocene Siwalik Group Fine to medium grained arkosic pebbly Siwalik Range - Pleistocene (Churia) sandstone, unconsolidated (Mountain) conglomerate. Fine grained, hard gray sandstone inter-bedded with purple coloured shale Permo - Takure Formation Sandstone, quartize sandstone, graphitic (Mountain) Corboniferous coals, chloritic phyllites Precambrian Seti Formation Gray to greenish gray phyllites, (Mountain) quartzites with minor conglomeratic The Terai plain was created by tectonic upheaval of Himalayas and development of fore deep of Indo- Gangetic basin a million years ago1. When Himalayas rose to this final shape, a fore deep was created in which Siwalik and older sediment layers sunk in the trough. Now Siwalik rock lies at a depth of 1.2 to 1.5 km below the Terai alluvium. The alluviums in Terai were deposited by sediment derived from nearby mountains. Lithology of top part of the alluvium beds is found to be similar to those rocks exposed in the nearby mountains. Not all rivers which are at presents flowing through Terai have contributed to the deposition. Only major rivers like the Koshi, having antecedent nature, had deposited first in the basin. Later on when other rivers came into existence, and they also started depositing the older material on the top part of the alluvium beds. The study area is underlain by unconsolidated alluvial deposit. This formation is irregular alternating beds of silt, sand and gravel. These deposits grade laterally and vertically into each other. Local boulders are found with a scattered pattern outcrops at a construction site of road and bridge. The unconsolidated sediment deposits are mostly pervious and make an excellent aquifer. 3.1.4. Soil Type and Quality Based on the result of Land Resource Mapping Project (RMP) which was conducted as a technical co-operation by the Canadian International Development Agency (CIDA), most of the study area is classified into the areas suitable for diversified crop due to the sandy soils except for limited spots scattered in Ghuski, Rajganj Sinuwari, Madhya Harsahi and Gautampur VDCs (see Figure 3-2). The sandy soil is found more as one goes to southern part of the study area. Number of soil samples were taken for the determination of the soil characteristics. The results of soil analysis have been summarized in (Table 3-3). Figure 3-2 : Areas Suitable for Paddy 1 Sedimentary environment on the Study area is based largely on Sharma C.K., 1995 Shallow Aquifers of Nepal. 3-3 Draft EIA Report of the Sunsari River Irrigation Project Existing Environmental Conditions Table 3-3 : The Result of Soil Analysis Classification Standard Max. Min. Low/ Medium/ High/ Items Deficit Adequate Toxic (1) Texture 65.8 %1) 35.8 %1) 22) 62) 112) (2) pH 6.0 - 8.0 5.7 7.2 5 14 - (3) Organic Matter 2.5 - 5.0% 9.7 % 0.7% 8 9 2 (4) Major Elements Nitrogen (N) - 0.28 % 0.03% 6 8 5 Phosphorous (P) 28 - 56 kg/ha3) 969 kg/ha 189 kg/ha - - 19 Potash (K) 112 - 280 kg/ha4) 591 kg/ha 836 kg/ha - - 19 (5) Micronutrients Boron (B) 20 - 60 ppm 80 ppm 44 ppm - 8 11 Molybdenum (Mo) 0.2 - 1.0 ppm 53.1 ppm 2.3 ppm - - 19 Zinc (Zn) 25 - 150 ppm 65.8 ppm 14.0 ppm 11 8 - Copper (Cu) 5 - 20 ppm 24.5 ppm 4.5 ppm 4 12 3 Iron (Fe) 50 - 250 ppm 153 ppm 63 ppm - 19 - Manganese (Mn) 20 - 500 ppm 680 ppm 250 ppm - 8 11 1) Contents of sand (%) 2) Low/Deficit: silt loam, Medium/Adequate: loam, High/Toxic: sandy loam 3) P2O5 basis 4) K2O basis 3.1.5.