Chapter 1: introduction

4.1 Project Impact Area

The project impact area is defined as the Project Districts, Project VDCs and Project area. The Project Districts are the districts where the project structures, facilities and river dewatering are located. For KAHEP, Project Districts are the districts of Panchthar and Taplejung. The Project VDCs of KAHEP comprise four VDCs namely Amarpur and Panchami of the Panchthar district and Thechambu and Nankholang of the Taplejung district where the project structures, facilities and river dewatering are located. The term “Project area” includes both Project Districts and VDCs.

Based on the potential environmental impacts of the project, the Project VDCs are further classified as direct impact areas and indirect impact areas:

1. 
   Direct Impact Area
   

This includes all the areas where construction and operation activities of the project and their implications are confined. In this area, environmental components will be directly affected by the project activities. These areas include project structural and facility sites and the river stretches, where the dewatering occurs such as headworks, settling basin, waterway, quarry site, muck disposal site, construction and operation camps, access and construction roads, dewatered zone along the river in between the barrage and Tamor River, the stretch of Tamor river that receives the final discharge of the power plant, and reservoir areas created by the barrage. The direct impact zone extends 250m surrounding the deginated areas of the project structures and facilities.

2. 
   Indirect Impact Area
   

The surrounding areas of the direct impact areas, not affected directly by the construction and operation activities but affected indirectly by the induced and allied activities of the construction and operations, are defined as the Indirect Impact Areas. They consist of forest areas and settlements within the Project VDCs and access roads.

The key settlement within the direct and indirect impact areas is presented in the Table 4.1 and Figure 4.1.

Table 4.1: Settlements in the Impact Areas

Project Districts (PD)	Project VDCs (PVDCs)	Settlements in the Direct Impact area	Distance in Meter	Settlements in the Indirect Impact Area
Panchthar	Amarpur	Dhuseni (HW, TA, AR),	250	Bhanuchowk
		Rajabesi (HW,DS, AR),	1000	Bhadaure
		Kabeli Bazaar (DS, AR),	2.5 km from HW	Kurledanda
		Dubichaur (TA)	400	Simle
		Phodarpati (TA)	600	Jarayotar
		Pinasi (PH, AR)	500	Madibung
Panchthar	Panchami	Kodekpa (PH,)	1000	Tilhar
Taplejung	Thechambu	Kharelgaun (DS)	2.5 km from HW	Khalte
				Chipnewa
Taplejung	Nangkholyang	Khaharegaun (DS)	3 km from HW	Myakha

Note: HW = Headworks, TA = Tunnel alignment, AR = Access road, PH = Powerhouse, DS =Dewatered stretch

Figure 4.1: Key Settlement within theDirect and Indirect Impact Area

4.2 Physical Environment

4.2.1 Topography and Geomorphology

The major part of the project area is located in the Mid-Mountain Physiographic Zone (LRMP, 1986). Characteristic of the Mid-Mountain Physiographic Zone is a ramification of the elevated mountaineous topgraphy (>1.500m) with intervening deeply entreched “V” shaped valleys (<700m). The higher mountain ranges and the principal valley generally extend northsouth whereas the minor mountains and tributary valleys extend in the eastwest direction. The physiographic distribution of the project area is presented in Table 4.2.

Table 4.2: Physiographic Division of the Project Area

Project District	Physiographic Zone	Area in Hectare (Ha)	Percentage (%)
Panchthar	High Himalaya	715	0.57
	High mountain	17,264	13.86
	Mid-Mountain	1,06,611	85.57
Subtotal		1,24,590	100.00
Taplejung	High Himalaya	16,588	20.93
	High Mountain	15,072	19.01
	Mid-Mountain	47,609	60.06
Subtotal		79,269	100.00
Total Panchhar and Taplejung	High Himalaya	17,303	8.49
	High Mountain	32,336	15.86
	Mid-Mountain	1,54,220	75.65
Total		2,03,859	100.00

Source: ISRSC, 2004

Geomorphologically, the area is still in the formative process. The steep mountain slopes, particularly the valley slopes and the upper middle hillslopes reflect the geomorphic dynamism of the area related to the mountain building tectonic activities (refer Figure 2.2, 2.4, 2.5 and 2.6). The general topographic forms reveal periods of active tectonism and tectonic quisence. The terraces at 2 to 3 levels at the Tamor valley and one or two levels towards the mouth of the tributary valleys reveal periods of tectonic quiscense and high degree of sediment deposition, whereas the steep valley mountain slopes, particularly the vertical topographic breaks between the alluvial terraces (Tars) are the product of high degrees of active tectonism related to the Himalayan uplift and active riverine erosion. The gentler lower middle, and upper middle mountain slopes reflect stabilisation of the landforms and mostly represent stabillised pre-historic landslide areas.

The general landuse in the project area is dictated by the geomorphic forms of the area. The alluvial tars of the valley, and the lower and middle mountain slopes are extensively used for agriculture and human settlement. The steep valley slopes and upper mountain slopes are either under the forest cover or are very steep represented by the bare rocks with the thin soil development.

Most of the project structures and facilities are located at the valley section represented by active alluvial flood plains or on alluvial tars. The headworks, reservoir and the intake structures are located on the active alluvial plain of the Kabeli river with altitude less than 600 masl. The diversion canals, settling basin and the headrace tunnel are underground structures (Refer Figure 2.5). The diversion tunnel and the settling basin lies beneth the relatively steep northwest facingvalley foot slope of the Kabeli on the left bank. The headrace tunnel passes along the eastwest direction extending mountainous ridge and connects to the underground surge tank located on the south facing valley at the foot slope of the Tamor River on the left bank. The penstock pipe, a surface structure, linking the surge tank to the powerhouse, lies over a rather steep and rocky valley foot slope. The powerhouse sructure is located in the alluvial tar of the Tamor and Piple Khola on the left bank of Tamor River. This alluvial tar is a fan deposit of the Piple Khola (refer Figure 2.6) and is being constantly changing its morphology owing to the erosional and depositional activities of Piple Khola even at the recent times and is likely to change in the future. The tailrace covered canal passes through the active fan of the Piple Khola and opens up on the left bank of the Tamor River a little downstream of Piple – Tamor confluence.

The quarry sites for the aggregate materials are located on the flood plains and sandbars of Kabeli and Tamor River (refer Figure 2.5 and 2.6). The muck/spoil disposal sites are also located along the flood plains along the left bank of Kabeli and Tamor Rivers. The construction camps, labor camps, aggregate storage, batching plants, etc. are located on the alluvial tars and gentler valley foot slopes of Kabeli and Tamor Rivers on the dominantly agricultural land use, high above the potential flood limits of Kabeli, Tamor, and adjoining tributary streams.

The active alluvial plain of the Kabeli River is reported to be changing its geomorphic forms depending upon the river floods and sediment deposition. The location of the river channel changes its course within the confines of the active flood plain. With the change in the river channel, the shape and size of the flood plain and the sand/boulder island bars also change. The high standing alluvial terraces (above 5m from the river bed) and the geomorphic forms of the sloping valley flanks are, however, stable (powerhouse camp areas) and are not reported to have changed their forms since the establishment of settlements in these areas. The Piple Khola alluvial fan at the powerhouse site is also reported to have changed its geomorphic forms frequently due to floods and debris slides in the catchment area.