Available online at www.sciencedirect.com ScienceDirect Aquatic Procedia 4 ( 2015 ) 713 – 720 INTERNATIONAL CONFERENCE ON WATER RESOURCES, COASTAL AND OCEAN ENGINEERING (ICWRCOE 2015) Spatial and Temporal Variability of Rainfall in Anand District of Gujarat State Khadeeja Priyan Civil Engineering Department, G H Patel College of Engineering & Technology,Bakrol Road,Vallabh Vidyanagar, Gujarat,388120,India Abstract Rainfall Variability is one of the key factors that affect agricultural production in any region. Hence the proper understanding of rainfall pattern and its trends may help water resources development and to take decisions for the developmental activities of that place. The present study is an attempt to evaluate the spatial and temporal rainfall variability of Anand district of Gujarat State in Western India. Anand in Gujarat State popularly known as the milk capital of India is located in the Southern part of Gujarat near Gulf of Cambay. The district has eight Talukas with district headquarter at Anand. Khambhat Taluka of this district has natural border with Gulf of Cambay. The normal rainfall of this district is 687 mm from South-West Monsoon with an average of 40 rainy days. The normal onset of monsoon is from 3rd week of June and the normal cessation is in the 4th week of September. In the present study the spatial and temporal rainfall characteristics of this district are studied. Long-term annual and monthly rainfall data (Monsoon months) are considered from 1901 to 2014. The daily rainfalls of monsoon months of all the eight Talukas are analysed for the last five years from 2010 to 2014. It was found out that spatial and temporal variability is high in the District. ©© 2015 2015 The The Authors. Authors. Published Published by byElsevier Elsevier B.V. B.V. This is an open access article under the CC BY-NC-ND license (Peerhttp://creativecommons.org/licenses/by-nc-nd/4.0/-review under responsibility of organizing committee). of ICWRCOE 2015. Peer-review under responsibility of organizing committee of ICWRCOE 2015 Keywords: annual and monthly rainfall, rainfall variablility, daily rainfall, number of rainy days. * Corresponding author. E-mail address: [email protected] 2214-241X © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of organizing committee of ICWRCOE 2015 doi: 10.1016/j.aqpro.2015.02.092 714 Khadeeja Priyan / Aquatic Procedia 4 ( 2015 ) 713 – 720 1. Introduction Rainfall variability is considered as an important factor in agricultural and other economic development. Hence understanding its nature and trend at any place has a great significance in water storage for future use. McCartney and Smakhtin (2010) stated that rainfall variability due to climate change and insufficient capacity to manage it, lead to poverty and food insecurity in Africa and some parts of Asia. Gujarat is one of the leading states in industrial developments in India, but the percapita water availability in this state is only 908 cum per annum which is far behind the national average. Though the State Government has taken a lot of steps to improve the water scenario, Sen (2010) recommended that all the stakeholders from the public and the private sectors should join together to create and manage the water resources. 1.1 Rainfall Variability Rainfall variability has been defined as the deviation of rainfall from the mean or the ratio of standard deviation to the mean or the variability of coefficient of variation (Rathod and Aruchami, 2010). Rainfall variability has been discussed and studied in the context of climate change at global level, regional level and local level. Gadgil (2007) emphasized that there should be a clear understanding of the basic systems responsible for monsoon and the factors that lead to its variation before developing any predictability model. Rangarajan and Sant, (2004) used fractal dimentional analysis to analyze the time series data of three major climatic variables – temperature, pressure and precipitation, to study variability changes and the variability of south-west monsoon and north-east monsoon in India at local level and regional level using predictability indices. They concluded that the precipitation during south–west monsoon is affected by the temperature and pressure variability of the preceding winter. Large sets of rainfall and temperature data are examined using spectral and time series analysis to analyse climatic trends and interactions (Tularam and Elahee, 2010). 1.2 Rainfall Variability in Gujarat The rainfall in Gujarat varies from 300 mm in the North and Northwest to gradually increasing to 2500 mm in the Southern districts (GEC, undated). The coefficient of variation of rainfall in the state is as high as 50%. Many hydrology projects have been taken up in the State with the objective of understanding the present institutional arrangement, technical capacity and physical facilities to the best level (Brahmbhatt, 2009). Many researches have been done in different parts of India to predict the rainfall variability. Varshneya, et al., (2009) forecasted the rainfall based on Astro-meteorology. Tripathi (2009) prepared a crop pattern by considering weekly rainfall pattern to help extension agencies to advise the farmers to prepare the crop plan which in turn helps to increase the agricultural productivity. The present study is an attempt to understand the spatial and temporal variability of rainfall in Anand district of Gujarat and the study reveals that high spatial and temporal variability over the period studied. 1.3 South West Monsoon in Gujarat State Gujarat state in India gets rainfall through South-West monsoon during June to September. The intraseasonal and inter annual variability of the summer monsoon has a great socio-economic impact in the agricultural and other economic development in India (Krishnamurthy and Kinter III, 2002). The study of the rainy season of India has been started even before 17th century and the scientific studies have been progressed in the post independence era with more understanding and prediction models (Sikka, 2012). It has been estimated that there is a large spatial variation in the annual rainfall of the country with a lower value of 35% in the sub-divisions of Tamilnadu & Pondicheri and with a maximum value of 95% in the subdivisions of Gujarat (Guhatakurta, 2012). Gujarat is one of the states in India where the highest one day rainfall exceeds 40 cm. As per the analysis of IMD for the period 1875-2009 maximum number of droughts occurred in Rajastan (31 years) followed by Gujarat (30 years). In the year 2008, the State experienced delayed and deficient monsoon and hence the net sown area was very less (Samui, 2012). Hence rainfall variability studies are having great significance in the State. Since the rainfall in the State varies from less than 500 mm in the arid Kutch regions to more than 2500 mm in the South Gujarat region, the Khadeeja Priyan / Aquatic Procedia 4 ( 2015 ) 713 – 720 715 study may be appropriate at micro-level only. 2. Study Area Anand district of Gujarat State in Western India popularly known as the milk capital of India is located at 2206’ to 220 43’ N latitude and 7202’ to 73012’E longitude with an altitude 43 m above MSL. This district is located in the Southern part of Gujarat near Gulf of Cambay. The district has eight Talukas with district headquarter at Anand. It is bounded by Kheda district on the North, Ahmedabad district on the West, Baroda district on the East and Gulf of Cambay on the South. Khambhat Taluka has a natural border with Gulf of Cambay. Amul (Anand Milk Union Ltd) Dairy, the largest dairy Cooperative of India and National Dairy Development Board are situated here. Ahmedabad –Mumbai Expressway is passing through the district. The district has a total area of 2951 sq.km and the total population is 2,092,745 as per 2011Census. There are eight Talukas in the district and out of the total geographical area of the district 70.5% area is cultivable area. The normal rainfall of this district is 687 mm from South-West Monsoon with an average of 40 rainy days. The normal onset of monsoon is from 3rd week of June and the normal cessation is in the 4th week of September. For the present study, rainfall data from Gujarat State Disaster Management Agency (GSDMA), Gandhinagar and Long sequence of district wise data available with Indian Meteorological Department (IMD) have been collected and analysed. Figure 1 . Administrative Boundary of (a ) Gujarat (b) Anand District There are eight Talukas (Anand, Anklav, Borsad, Khambat, Petlad, Sojitra, Tarapur and Umreth) in Anand 716 Khadeeja Priyan / Aquatic Procedia 4 ( 2015 ) 713 – 720 District and the spatial and temporal variations in rainfall are very high in these Talukas. The average rainfall in the district from 1984-2013 was 763 mm where as the State average was 797 mm. The average rainfall values of last 30 years in these Talukas are shown in Figure 2. The average annual rainfall of last 30 years (1984-2013) shows that the highest value 910 mm was recorded in Anklav Taluka and the lowest value 599 mm was recorded in Umreth Taluka. The same pattern for highest and lowest rainfall was observed in Anklav Taluka and Umreth Taluka respectively when the 10 years averages of (2000-2009) and (2001-2010) are considered. Umreth Taluka is the farthest Taluka of this district from the sea coast. Anand, Anklav, Borsad, Khambat and Petlad recorded above normal rainfall of the district. Sojitra, Tarapur and Umreth have received below average rainfall only. In general, Talukas in the northern side of the district recorded below average rainfall during the last 30 years.