Environmental Resource Information on Pampa River Basin
The mean water temperature in the different stretches in River Pampa (Kochu Pampa-upper stretch, Kozhencherry-middle stretch, Neerettupuram-lower stretch & Pallathuruthy-estuarine stretch) of the river varied between 21.7 to 330c. The dissolved oxygen levels depicted low to moderately high values ranging from 4.5 to 7.8 mg/l in all the stretches except in the estuarine stretch where the value dropped to 2.2 mg/l during the premonsoon, and the carbon dioxide value rose to 12.4 mg/l, which could be due to the discharge of municipal waste in to this zone. The principal change noticed during the study in all the study stations of the river was lowering of mean alkalinity and total dissolved solid level to 16.5 mg/l and 29.7 mg/I respectively. The dissolved nutrient concentration was highly influenced by the monsoon discharge (Biju Vikram and Jha, 2003).
The nitrate and phosphate contents showed slightly higher values in the lower and estuarine stretches (Nitrate-1.32 and 0.07 mg/I and Phosphate-0.04 and 0.01 mg/I) which was due to the high domestic and sewage discharge and agricultural run off in to the river system. The high COD values in the lower (40 mg/l) and estuarine stations (35 mg/l) clearly indicate the high organic load leading to intense pollution in the water body. Biju Vikram and Jha 2003. Several reports have established that the bicarbonate levels were low in the Kerala rivers, compared to the peninsular rivers of India.
In the Pampa river, the major planktonic organisms collected from various stretches in the river were Anabena, Ankistrodesmus, Chlorella, Navicula, tintinnids, Pleurosigma and Microcystis. Benthic population consisted of Chironomus larvae, polychaetus(Dero sp. Nereis.sp), Tubifex sp, insect larvae, gastropods and bivalves. The algal and benthic biomass and diversity was generally low in most of the stretches. According to a study by Biju Vikram and Jha (2003) 69 species of indigenous fishes and 10 species of exotic/non-native fishes contributed to the fishery of the river during 2003-04 period. Commercial fishery was supported by 57 species recorded in this study. According to the IUCN classification, 30 species can be treated as threatened of which, 5 species Labeo dussumieri, Puntius, denosnii, Horabagrus brachysoma, Tor khudree and Hypselobarbus curmuca belonged to the endangered group. The two species clarius dussumieri and channa punctatus were absent. The annual catch declined by 34% during 1999-2003 period in the Pampa river. The upper stretch was dominated by exotic fishes and replaced the endemic fishes like Tor khudree and Hypselobarbus curcuma. An increase in the catch of exotic fishes in river system was due to the introduction of these fishes in the reservoirs in upper stretch by Kerala Forest Development Corporation.
Recent investigation at the Cochin University of Science & Technology, reported 174 fish species under 13 orders, 29 families and 65 genera were collected and identified from the rivers and streams of Kerala. The species identifies from Pampa from the study according to their status were, Chandanama (low risk), Channa marulius (Vulnerable), Channa micropeltes (Critical), Gara Mullya (Low risk)Labeo dussumieri (endangered), Labeo rohita (low risk), Mastacembeles armatus(low risk) Nandus nandus (low risk), Nemacheilus seminarmatas(vulnerable), Orechromis mossambicus (introduced), Parambassis dayi (vulnerable), Puntius barmanicus, pantius filamentosus (low risk).
Harikumar et.al studied the water quality of Pampa river and found that the pollution was due to the open defecation, bathing and overflow from the earthen tanks filled with excreta. These total coliforms count was determined to vary from 4000 to 78000 MPN/100ml.
(Source: Impact on Human intervention on the Biophysical environment of rivers. Biju Vikram and Jha)
Drainage: Pathanamthitta district
Pamba Manimala, Achenkovil and Kallada rivers along with this tributaries constitute major drainage of Pathanamthitta district.
Pamba River: Pampa, the mighty river of 7th order in magnitude rises from the Naga Mala(1830 m) of the hilly rugged terrain of Pathanamthitta district within the domain of Gudarakal Reserved Forest Area. It is confluenced by two major streams- Mukkari Todu (4th order) and Chinnamaelmala Ar. (5th order)Chinnamelmala Ar originates in the hilly areas of Chinnamel Mala (1487 m), where radial drainage pattern is the dominant feature.
Pampa reservoir (2.50 km2) area has been formed at 1000 m elevation. From here Pampa Ar flows in a meandering course through steep escarpments particularly in the left bank and receives tributaries Nand Ar and Kullar both of 4th order in magnitude. Pampa Ar further flows in a Southwesterly course through hilly area with the stream base of 200m until it confluences with major stream- Kakki Ar at 170 m above MSL approximately 500 metre east of Triveni.
Source: Natural Resource inventory for Alappuzha and parts of Pathanamthitta Districts falling within Pampa catchment.
Basin characteristics: Pampa river
Morphometric analysis to appraise the basin characteristics has been undertaken for the Pampa river. The term morphometry means measurement and analysis of form characteristics. The drainage basin is a perfect setting where this type of quantitative approach can be applied because it is the fundamental unit of land forms in fluvial terrain (chorley, 1972), River channels comprise only a small part of the total landscape, yet their significance far out weighs their areal extent (Schumm, 1971). Topographic evolution of the fluvially eroded land forms may be explained by tree variablles, viz structure, process and stage as elucidated by Davis (1899). In order to assess the development of drainage basin in quantitative terms, several parameters have been analysed numerically.
Pampa is a 7th order stream which flows for 176 km through Pathanamthitta & Alappuzha districts.
The total basinal area of the river covers 2235 km2 1549 km2 of Pathanamthitta district comes under Pampa catchment.
The entire basin has been subdivided into major and minor sub basins taking into account the area drained individually by well developed branching streams of different orders which are demarcated as major and minor water sheds.
Pampa river network has been subdivided into 6167 first order basins.
Cumulative stream length (inclusive of all orders) in the Pampa basin is nearly 44.66 km.
Drainage density is one of the most useful variables in analysing basin characteristics, as this may be correlated with the dynamic nature of the drainage network and the area of the basin.
Drainage density is the average length of stream within the basin per unit of area. The poorly drained basins have density of 0.73 km/km2, where as the well drained one vary from 2 to 4 or more depending upon the various physiographic controls like rock hardness, amount of precipitation in filteration capacity of soil etc.
Average drainage density of Pampa basin is 2.96 km/km2. Average drainage density of 6th order streams is 3.54 km/km2.
Drainage density increases in the lower order. Drainage basins which all are situated in the high land, eg: sediment source zone, and it decreases towards the lower reaches of the river due to less number of tributaries, reduction in rainfall and of loss of relief.
The longitudinal profile of a stream is described by its continuous fall in elevation and the horizontal distance, between the source and the mouth. From the longitudinal profile of the Pamba river, abrupt fall of 200 metre from 1300 to 1100 metre and a fall of 500 m from 1000 to 500 m within a small distances of 1.25 km and 2.50 km are observed.
Pulikeezh block consisting of Kadapra, Kuttoor, Niranam, Nedumpuram and Peringara Panchayats is situated in the extreme western side of the district, display varied physical features, drained mainly by Pampa river.
Koipuram block consists of Ayiroor, Eraviperoor, Koipuram, Thottapuzhasserry, Ezhumattoor and Puramattom Panchayats are drained by the first and second order streams of Pampa and Manimala.
Elanthoor, Cherukole, Kozhencherry, Mallapuzhasserry and Naranganam consistude of Elanthoor block are drained by Pampa river.
Pollution of a river generally prevades the environment. Although, the quality criteria for standard drinking water has been well laid down, the question of safety aspect of drinking water has still remained more a concept than a reality. The everyday consumable water could lie any where between two extreme sides depending upon a large no. of interrelated factors.
In the view of complexities associated with riverine pollution and its widespread impact on human society, an attempt has been made to quantify pollution levels of the Pamba river and to link with land use and anthropogenic causes.
Physico-Chemical and microbiological parameters of water and sediment samples from the Pampa river indicate extensive deterioration in water quality, especially close to the pilgrimage site, as well as in the proximity of population centres. Other stations show relatively better quality. This implies that adoption of proper sanitation measures and sewage disposal are essential for preserving the Pamba water quality. Polluted water discharge from Pamba renders the upper kuttanad are highly vulnerable to water-borne contageous diseases.
Results and Discussion
Physio chemical parameters-Pamba river (Oct. 98)
Water with pH values ranging from 6.5 to 7.5 is considered normal. pH values in Pamba basin ranged from 6.08 to 8.22. The tendency to be alkaline (higher pH) at the downstream locations is attributed mainly to the mixing with waste, waters, containing bicarbonates and chlorides
Temperature plays a vital role in controlling the physical and chemical characters of water. It has been shown that low temperature decrease the effectiveness of chlorination. Increased temperature may also cause bad taste and odour in water due to increased voltality of odour causing compound. Temperature of the Pamba water column ranged from 230c to 28.50C.
Dissolved oxygen level: (DO)
Dissolved oxygen levels in natural water depend on the physical, chemical and biochemical activities in the water body. Do values in Pamba river ranged from 2.24 to 6.01 mg/I
Biochemical oxygen Demand : (BOD)
BOD is a means to determine the relative oxygen requirements of waste waters, effluents and polluted water. Higher BOD values were recorded as 1.28 mg/I.
Nitrite-Nitrogen values varied from 0.09 to 2.09 m mol/I
Nitrate-Nitrogen: The Nitrate-Nitrogen values from 0.89 to 4.30m mol/I
Concentration of organic phosphate is low, ranging from 0.10 to 3.62 m mol/I
Chloride is the form of Chloride ion, is one of the major inorganic anions in water. In potable water, the salty taste produced by chloride concentration is variable and dependent on the chemical composition of water.
Maximum permissible limits for chloride content in drinking water is 200-500 mg/I. In Pamba river, Chloride content ranged from 8.70 to 80. 70 mg/I during different sampling seasons.
Alkalinity: Alkalinity is the measure of buffering capacity of water. It is an anionic phenomenon. All anions such as CO3 (Carbonate), HCO3 (bicarbonate) OH (hydroxyl ion), PO4 (Phosphate) and SiO4 (Silicate) Contribute to alkalinity of water.
Hardness: Hardness is one of the important parameters for quality determination of water for human consumption. The sulphate, Chloride and nitrate of Ca and Mg form the non-carbonate or permanent hardness in water. Pamba water showed wide-range variation of 5.40-52.0 mg/I
Calcium: Calcium is one of the alkaline earth metals. It is presently nearly in all waters with wide distribution. Permissible limit of calcium content may range from 75 tom 200 mg/l calcium content in the Pamba water varied from 1.10 to 9.62 during the sampling seasons.
Magnesium: Magnesium is a common constituent of natural waters. It has higher solubility than that of calcium and being bivalent produces hardness. permissible limit varies from 30-150 mg/I. Mg content is very meagre in Pamba river, it varied from 0.30 to 1.80 mg/I, in general during the sampling seasons with sporadic rise up to 6.80 mg/I
Total suspended solids (TSS)
Pamba river water displayed wide range of TSS value with maximum attainment of 528.7 mg/I
E.coli, Vibro Parahaemolytics like organisms (VPLO) Vibro Cholera like organisms(VCLO), Streptococcus faecaliscades like organisms (SFLO), Shyella like organisms (SHLO), Proteas Klebsilla like organisms (PKLO) were noted down and the findings for water as well as for sediment were present.
The Pamba river has become polluted to a great extent. Increased influx of pilgrimx and the insufficient sanitation facilities aggravated the problem. Sewageand Industrial effluents disposal into the river should be controlled. Deforestation in the upper catchment areas of the river should be checked to keep the river free of total suspended solids (TSS) as a result of intense erosion. Sand mining from the river bed as well as from the banks also contribute to change in elemental composition and pollution levels. Bathing of people and cattle, washing etc in the river itself should be regulated by providing side ponds. Upper catchment conservation measure through afforestation must also be initiated to check soil erosion and to accelerate the seepage flow.
Water Quality Deterioration
Sampling results from Pamba river indicate that TC (Total Count) and E.coli counts are higher than most other rivers in Kerala. There exists a direct relation between higher TC and FC counts and NO3-N in stations close to the pilgrim sites and other population centres. In between stations show lesser counts. This indicates that there is a spatial correlation between the analytical data and human impacts.
Pamba river bed is shared by fifteen Grama Panchayats. Out of these Kozhencherry Panchayat does not have any sand mining sites within its administrative boundary. A total of 23 sand mining locations (Kadavus) have been permitted for sand mining at a rate of 25 truck loads per day per kadavu by the Revenue Department (Padmalal et.al 1999). Estimates of sand mining indicate that 2044 m3 of sand is being mined daily from the river, between Edathikavu kadavu and Pandanad. It is conservatively compuled that on an average, 408800m3 of sand is being mined annually from the river channel, as against an annual replenishment of 17734 m3. This clearly shows that the sand accumulation from the river bed is being excavated with adverse impact on river bottom topography, ground water availability, water table fluctuation and vegetation cover.
The provenance zone of Pamba Ar. Kakki Ar and the western side of Kakki and Pamba reservoirs are more fragile in nature which calls for adopting conservation measures to maintain the ecosystem.