[DPR (Detailed project report for diversion of Yettinaholé to dry arid regions)]
Yettinaholé and streams in the catchment are perennial which cater to the users demand in the downstream. Karnataka Neeravari Nigam Limited, Government of Karnataka has proposed to divert and store the water to meet the needs of the water scares regions: Kaduru, Arsikere, Tipturu, Chikkanayakanahalli, Gubbi, Madhugiri, T.G.Halli, Ramnagara, Gouribidnuru, Nelamangala, Hesaraghatta, Doddaballapura, Hoskote, Devanahalli, Chikkaballapura, Gudibande, Bagepalli, Chintamani, Srinivasapura, Sidlaghatta, Maluru, Kolar, Mulbaglu and Bangarpete at an estimated cost of 12912 crores. The proposed weirs have overall catchment area of 176 sq.km with evergreen forests dominating the catchment to an extent of 45.05%, followed by agriculture plantations (coconut/arecanut) about 29.25% and grass lands about 24.06%. The presence of these thick evergreen forests and grass lands in the catchment are responsible for higher infiltration and perennial streams. Any anthropogenic activities involving large scale land cover changes would affect the hydrology of the river basin affecting the dependent biota. The region’s ecological and economic importance is evident from

• Yettinaholé and its immediate neighboring catchments falls under the Ecological Sensitive Zone 1 (ESZ 1) (HLWG report of Western Ghats conservation, http://envfor.nic.in/sites/default/files/HLWG-Report-Part-1_0.pdf) and as per the recommendations of the working group there shall be strictly no developmental activities.
• The region is vulnerable and prone to frequent human animal conflict (Elephant Human conflict) as per the Karnataka Elephant Task Force (KETF: (i) http://envfor.nic.in/content/report-karnataka-elephant-task-force-submitted-honourable-high-court-karnataka?theme=moef_high, (ii) http://www.atree.org/sites/ default/files/KETF%20Final%20Report%20SCREEN%20RES.pdf#page=14&zoom=auto,-12,418), and any alterations in the elephant corridors would enhance human animal conflicts threatening the survival of elephants.

As per DPR (Detailed project report for diversion of Yettinaholé to dry arid regions) by the Karnataka Neeravari Nigam Limited the hydrologic yield in the catchment is 24 TMC. But actual water yield in the catchment is 9.55 TMC based on field data collection coupled with the assessment based on the rainfall data (the directorate of economics and statistics (GOK) and India Meteorological Department, Pune).  Water yield in the catchment is 9.55TMC based on the stream gauging in select streams, and indirect estimation considering rainfall in the catchment (vary from 3500mm to 4000 mm) and current land uses. Computed catchment yield (based on the empirical relationship - hydrological model) compared with the gauged values of the runoff (maintained by KPC: Karnataka Power Corporation Limited), indicate that estimated values are comparable to gauged values: estimated value of the water yield is 0.702 TMC compared to 0.813 TMC (gauged at Kadumane holé 1- maintained between 2009 and 2012, Annexure Table 18). An accuracy of the model is 86.1% (Table 15) and hence the current approach was used for estimating the yield in the catchment of ungauged streams. Table 15 lists water yield in the catchment based on the current study and values mentioned in the DPR, which indicates exaggeration of values (total water yield is only 9.55 TMC compared to 24.03 TMC indicated in DPR).

Table 15: Comparison of DPR and the Hydro-meteorological analysis

Estimate of water yield of 24.03 TMC in Yennaeholé catchment in the DPR is on the assumption of annual rainfall of 6280 mm, without considering the variability across regions. Rainfall varies between 3500mm (Yettinaholé catchment) and 4700 mm (Kadumaneholé 1 catchment). Table 19 depicts variations in the runoff yield in 8 catchments, which was estimated (i) based on the gauged readings at Bantwala by CWC, (ii) proportional areas and spatial variation in the rainfall pattern were considered to derive the catchment yield, as per equation 12.

Where 
Qn = Flow at weir n
Q = Flow at Bantwal
An = Catchment area at weir n
A = Catchment area at Bantwal
Pn = Weir n catchment average rainfall
P = Bantwal catchment average rainfall
Computation of the catchment yield in Yennaeholé catchment shows a yield of 9.55 TMC in contrast to the claim of 24TMC as per DPR. The hydrological model considers the spatial extent and type of elements of the landscape (namely forests, agriculture, horticulture, grass lands, plantations, open lands etc,) with the meteorological information. The hydrological model also takes into consideration various demands namely: crop water requirement, domestic water requirement, livestock water requirement, evaporation losses; which accounts to be 5.8 TMC in a year (table 14), which are not accounted in the DPR.
Hydrology yield computed is comparable to

• Computations by Mayya S G (NITK Surathkal), Paramashivaiah (Hydrologist) [TV 9 news channel discussion dated: Jul 23, 2013- https://www.youtube.com/watch?v=dQDaaA6W8mI] indicate that the water yield is  about 8 – 10 TMC (comparable to our calculated value of 9.55 TMC per year). This highlights that drawing waters to cater the needs of drinking water in the neighboring district would be an illusion as there is insufficient water to meet all demand in the catchment.