International Journal of Scientific & Engineering Research Volume 6, Issue 10, October-2015 803 ISSN 2229-5518 Irrigational quality of Vamanapuram River, Kerala, India Vinod Gopal, V* and Sabu Joseph Abstract— Surface water is treated as an important source for irrigation around the world. The composition and concentration of dissolved components in water determine its quality for irrigation. One of the important considerations of water quality for irrigation is the saline or alkaline nature of the water. Characteristics of irrigational water can vary with the source of the water which may directly affects the management of soils and crops, and their associations. Assessment of irrigational quality of Vamanapuram river was carried out by means of Electrical Conductivity (EC) or Salinity index, Total Dissolved Solids (TDS), Chlorinity Index (CI), Sodium Adsorption Ratio (SAR), Soluble Sodium percentage (SSP) or Per cent Sodium (Na%), Residual Sodium Carbonates (RSC), Residual Sodium Bicarbonates (RSBC), Magnesium Adsorption Ratio (MAR), Permeability index (PI), Kelly’s Ratio (KR), Corrosivity Ratio (CR) and Hardness. Water resources in the highland and midland parts of the study area (i.e., S1 to S16 and T1to T3) are within the range. Samples from lowland are highly influenced by salinity, Fe and chlorinity. Index Terms— Vamanapuram, irrigational quality, EC, TDS, CI, SAR, SSP, Na%, RSC, RSBC, MAR, PI, KR, CR —————————— —————————— 1 INTRODUCTION 2 METHODOLOGY Rivers are historically recorded as the centre of civilization Sampling and analysis of quality parameters such as pH, and development. The streams and their associated electrical conductivity (EC), total dissolved solids (TDS) or floodplains have immense contribution in their origin and salinity index, total hardness (TH) and Chlorinity Index (CI) or cultural progress and still remain so. The Nile River Valley chlorinity were estimated by standard methods[5] and the Civilization started at the northern most peak of the Nile River important irrigational quality parameters were computed by at the time of the Neolithic Revolution. Around 4000 B.C the the following equations: Yellow (Hueng He) River valley Civilization began in China. In India, The Indus River Valley Civilization started about Na SAR = (1) 2500 B.C. along the south-western part of the Indus River. The 2 2 largest city was Mohenjo-Daro and settlements stretched all Ca Mg along the river have the patent of all our cultural resources. 2 Urbanization and adopted trends in land use pattern or input SSP = KNa (2) 2 2 u100 of urban stress to natural streams, challenges the integrity of Ca Mg Na K water quality. Water used for agriculture should be in range of RSC = (CO3 +HCO3) __ (Ca+ Mg) (3) 2 standard chemical behaviour. The land practices and nutrients RSBC HCO 3 Ca (4) and pesticides to rivers as leachout shall affect biological Mg 2 MAR u 100 (5) integrity. The differences in the characteristics of water are a Ca 2 Mg 2 result of variations in the geology, climate and climatic [1] Na HCO parameters . PI 3 u 100 (6) Ca 2 Mg 2 Na Deshpande and Aher[2] attempted to understand water rock interaction process and to investigate the concentration of the Na KR (7) total dissolved constituents present in the ground water with Ca 2 Mg 2 respects to the standards of safe potable water. An attempt has Cl mg L SO 2 mg L been made to evaluate the quality of groundwater for 4 CR = (8) [3,4] 35 5. 48 irrigation purpose . 2 [ HCO 3 mg COL 3 mg L ] Vinod Gopal, V* -Research Scholar, Department of Environmental 50 sciences, University of Kerala, Kariavattom Campus, Thiruvananthapuram All the ionic concentrations in the above equation are -1 Sabu Joseph- Associate professor, Department of Environmental sciences, expressed in meq L and %Na, MAR and PI in %. 25 samples University of Kerala, Kariavattom Campus, Thiruvananthapuram (19=river, 4=tributary, 1=estuary) were collected for each season (monsoon- MON, Post-monsoon-POM and Pre- Corresponding Author- [email protected] monsoon-PRM) approximately 5 km interval (mainstream). The sixth order Vamanapuram river originates from the upper slope of Western Ghats in southern Kerala and debouches into International Journal of Scientific & Engineering Research Volume 6, Issue 10, October-2015 804 ISSN 2229-5518 the Anchuthengu lake. It flourishes 29 panchayats and classified based on the chlorinity index[12,13] majority of the Attingal municipality. Majority of study area falls in surface water samples (20) were fall in Class I and are suitable highlands, 56.1% (385 sq.km) followed by midlands (40.7%) for irrigational purpose due to the low saline nature but some and lowlands 3.2% (22 sq.km). About 1/56th of the area of of the samples from the study area were included in class V Kerala State is managed altogether by this small catchment are Unsuitable for irrigation (Table: 4). [6] river and its tributaries which meets 1, 18, 499 people . 3.4. Sodium Adsorption Ratio (SAR) Midland to lowland regime of main stream (43 km) possesses 16 pump houses and 11 water intake points. Fig.1 shows the Sodium adsorption ratio is the proportion of sodium to study area with drainage networks and sampling points. The calcium and magnesium, which affect the availability of the [14] study area faces 41% degradation since 1967 to 2011 in paddy. water to the crop . The sodium adsorption ratio gives a clear The assessment of irrigational quality of surface waters of idea about the adsorption of sodium by soil; higher values of Vamanapuram river is the main objective of the study. sodium in irrigation water resulting in poor drainage. High values of SAR imply a hazard of sodium replacing adsorbed 3 RESULTS AND DISCUSSION calcium and magnesium, a situation ultimately damaging to [15] The concentration of chemical constituents in irrigation water soil structure . directly affects plant growth through toxicity or deficiency, or The SAR is used to predict the sodium hazard of high indirectly by altering nutrient unavailability[7,8]. Use of carbonate waters especially if they contain no residual polluted water for irrigation can create four types of problems, alkali[11]. namely toxicity, water infiltration, salinity and The alkalinity hazard of water samples are shown in the Table: miscellaneous[7]. Irrigational water quality of surface water 5. According to Rao[16], majority of the water samples were fall samples of VRB is depicted in Table 1. within the excellent quality during the MON (24), POM (20) 3.1. Electrical conductivity (Salinity index) and PRM (19) seasons. In the POM and PRM seasons some of The most influential potent tool in water quality guideline on the samples were (S5 and S6) become unsuitable due to crop productivity is the water salinity hazard as measured by sodium hazard. Comparatively in MON the water showed electrical conductivity (EC). Salinity is related to TDS and EC; high quality, it might be due to the high dilution. it reflects the TDS in water. High concentrations of TDS and USSL Diagram EC in irrigation water may increase the soil salinity, which affects the plant salt intake. Based on the sodicity (USSL) diagram the surface water samples are classified and shown in Fig. 2 to 4. The USSL EC of the VRB in three seasons and comparison with the EC diagram of the water samples of VRB indicates that majority of classification table[9] and it was found that majority of the the samples have low SAR value. In all the three seasons, out water samples (20) in the VRB are low saline water and are of 25 samples, 19 samples lies in C1-S1 field and it is excellent for irrigational purpose according to the values of EC considered as good water category for irrigation use. in all the three season. A few exemptions are observed in the water samples which were collected from the tributaries of In PRM, six water samples were fall in the C4-S4 category, Vamanapuram river and are showing excessive salinity (T4) in while in MON it was only one and in POM it is five. It all the seasons, are unsuitable for irrigational purpose indicates very high alkali hazard and these waters are (Table:2). unsatisfactory for irrigation under normal condition. Three 3.2. Total Dissolved Solids (TDS) water samples in MON were fall in the C4-S3 category and it denotes very high in salinity and high sodicity waters and two High cationic representation in the irrigation water may prove samples were in the C4-S2 category (very high in salinity and [10] to be injurious to plants and animals . When present in medium sodicity). In POM, one sample was in the C3-S1 field excessive quantities, they reduce the osmotic activities of the indicates high salinity and low sodicity. The exceptional plants and may prevent adequate aeration, causing injuries of character (very high alkali hazard) shown by the six surface plant growth. water samples of VRB are in close vicinity of salt waters from Table: 3 showing the classification of the water samples based sea and estuary; and the fluctuations in the season might be on the TDS content[11]. From the table it could be understood due to the dilution. that majority of the water samples (20) were best quality in all 3.5. Soluble Sodium Percent (SSP) or Percent Sodium (% Na) seasons and can be used for irrigation without any treatment. The pore space of the soil contains air and water and is 3.3. Chlorinity Index (CI) required for the proper growth of plants. The Sodium content The chloride ion can be toxic to plants having high salt of water reacts with the soil and accumulates in the pore tolerance when taken up by their roots and absorbed through spaces thus reducing its permeability.