INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 7, No 2, 2016 Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0 Research article ISSN 0976 4402 Climate change evaluation for Ozat basin of Saurashtra region of Gujarat, India Paradava D.M. 1, Rank H. D. 2, Kelaiya J.H. 2, Trivedi M.M. 1 and Chinchorkar S.S 1 1- Polytechnic in Agricultural Engineering, Anand Agricultural University, Dahod-389151 (Gujarat). 2- Department of soil and water conservation, College of agricultural engineering and technology, Junagadh Agricultural University, Junagadh-362001 (Gujarat). dmparadava@aau.in doi:10.6088/ijes.7016 ABSTRACT The impact of global climate change on crop production has emerged as a major research priority during the past decade. The understanding of the significance of warming shocks on agriculture and spatial unevenness of warming tendency on planet earth had led the present the study on climate change evaluation in Ozat basin (3176.24km 2 ) having four watersheds. The time series of monthly, seasonal and annual average of daily maximum, minimum and mean temperature along with solar radiation (1979-2013) for each of four watersheds and basin were examined separately using Mann-Kendall, Sen s slope and best fit trend line methods. The seasonal and annual series of daily minimum and mean temperature were found significantly increasing in all four watersheds and basin also. The seasonal average of maximum temperature was significantly increasing during winter (0.3o C/decade) and annual (0.1 oc/decade). However, the seasonal average of daily minimum and mean temperature were found increased significantly at 0.3, 0.3, 0.2 and 0.3 oc/decade and 0.3, 0.2, 0.1 and 0.2 oc/decade respectively during winter, summer, monsoon and annual. The solar radiation was found significantly increasing during monsoon but insignificantly during rest of seasons. The warming trend was detected in Ozat basin. The cereal crops like wheat may be replaced by some oilseed or pulse crop due to warming trend. Keywords: Climate change, temperature, mann-kendall, sens s slope, warming trend, Ozat basin. 1. Introduction Agricultural impacts due to climate change have received considerable attention in India as they are closely linked to the food security and poverty status of a vast majority of population. These climate changes in the past geological time had profound influence on sea level, rainfall patterns and temperature related weathering processes. Most of the evidences of past climate change, however, are circumstantial. The combination of a unique level of temperature increase in the late 20 th century and improved constraints on the role of natural variability provides further evidence that the greenhouse effect has already established itself above the level of natural variability of the last 1000 years and is greater than the best estimate of global temperature change for the last interglacial period. The global warming potential of carbon dioxide was estimated by the Swedish Chemist Svante Arrhenius and subsequently many researchers concluded that human consumption of fossil fuels was leading to significant increase in atmospheric-co2 and global average temperature (Callender 1938). Huang et al. (2000) have reported 20 th century to be the warmest of the past five centuries and later Huang (2004) reported 20 th century warming is a continuation to a long- Received on May 2016 Published on September 2016 174
term warming started before the onset of industrialization. The 4 th Assessment Report of IPCC (2007a) has also mentioned that the change in earth's climate has been in an unprecedented manner in the past 40,000 years, but greatly accelerated during the last century, due to rapid industrialization and indiscriminate destruction of natural environment. Climate change and agriculture are interrelated processes both of which take place on global scale. Global warming is projected to have significant impacts on conditions affecting agriculture, including temperature, CO2, glacier runoff, precipitation and the interaction of these elements. These conditions in term determine the carrying capacities of different ecosystems to produce enough biomass including food for human population and domesticated animals. The overall effect of climate change on agriculture will depend on the balance of these effects. Assessment of the effects of global climate change on agriculture might help to properly anticipate and adapt farming to maximize agricultural production. At the same time, agriculture has been shown to produce significant effects on climate change, primarily through the emission of GHGs as about 12.5% of total emission is from agricultural products globally. Land use change such as deforestation and desertification, together with the use of fossil fuels are the major anthropogenic sources of carbon dioxide. The various assessment reports brought out since 1990s by the IPCC have reconfirmed that the global atmospheric concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) have increased precedent. The increase in greenhouse gases(ghgs) was 70% between 1970 and 2004 and the IPCC has shown through a series of observations and modeling studies that these increases in GHGs have resulted in warming of the climate system by 0.74 o C during 1906-2008(Aggarwal,2008).The IPCC(2007a) has projected that the temperature increase by the end of this century is expected to be in the range of 1.8-4.0 C and it is also likely that future tropical cyclones will become more intense with larger peak wind speeds and heavier precipitation. Increase in the amount of precipitation are likely in high latitudes while decreases are expected in most sub-tropical land regions, continuing observed patterns in recent trends. The projected sea level rise by the end of this century is likely to be 0.l8-0.59m (Aggarwal, 2008). The IPCC (2007b) has projected 0.50-1.20 o C rise in temperature by 2020, 0.88-3.16 o C by 2050 and 1.56-5.44 o C by 2080 depending upon the scenario of future development in south Asia including India. Enhancing agricultural productivity, therefore, is critical for ensuring food and nutritional security for all, particularly the resource poor small and marginal farmers who would be affected most. In the absence of planned adaptation, the consequences of long-term climate change could be severe on the livelihood security of the poor. Keeping in views of importance of warming impacts on agriculture and spatial variability of warming trend on planet earth, the present effort aims to study climate change assessment for Ozat basin of Saurashtra region, Gujarat state, India. 2. Methodology The downscaled global climate model simulations(cmip3) data (1979-2013) of daily maximum and minimum temperature( o C) and solar radiation (MJ/sq.m) for total 10 weather grid points falling in basin were used for the analysis. The monthly, seasonal and annual average weather parameters were estimated taking average of weather parameter of days of the respective periods. 175
2.1 Climate change and Indian agriculture India is a vast country covering 3.28 million km 2, occupying only 2.4 per cent of the world s geographical area but supporting 16.2 per cent of the global human population. It is endowed with varied climate supporting rich biodiversity and highly diverse ecology. More than sixty percent of its population is dependent on climate sensitive activities such as agriculture. Climate change projections made up to 2100 for India, indicate an overall increase in temperature by 2-4oC with no substantial change in precipitation quantity. The expected changes in climate, especially rainfall, are also marked by significant regional variation, with the Western Ghats, the Central Indian and the North Eastern regions projected to receive more rainfall compared to the other parts of India. Further, an increase in intensity and frequency of extreme events such as droughts, floods, and cyclones is also projected. All these changes are likely to have adverse impacts on India s water resources, agriculture, forests and other ecosystems, coastal zones, energy and infrastructure and on human health. [K.S.Kavi Kumar, 2010].The climate change was assessed by the trend analysis of the different time series data of maximum, minimum, mean temperature and solar radiation using the standard method as described by Gilbert (1987) and Kendall and Gibbons (1990) along with best fit trend analysis. 3. Result and discussion The trend analysis of monthly, seasonal and annual average of weather parameters like daily maximum, minimum, mean temperature and solar radiation for Ozat basin is given in Table- 1&2 and Fig 1 & 2. Table 1: The trend parameters of monthly, seasonal and annual average of weather parameters like daily Tmax, Tmin, Tmean( o C) and solar radiation (MJ/m 2 ) for Ozat river basin. Sr. No 1 2 3 4 Parameters Daily maximum temperature- Tmax( o C) Daily minimum temperature- Tmin( o C) Daily mean temperature- Tmean( o C) Daily mean solar Radiation(MJ/sqm) Period Increasing trend Significant (No.) Insignificant (No.) Decreasing trend Significant (No.) Insignificant (No.) Month 5 2 1 4 Month 10 2 - - Month 7 4-1 Month 2 7-3 3.1 Temperature Trend 3.1.1 Watershed 5G1C2 3.1.1.1 Monthly average Tmax, Tmin and Tmean Out of twelve month in a year, the monthly average maximum temperature was found increased during four month i.e. January (10% level), March (5 % level), November (1% 176
level) and December (5% level). The monthly average minimum temperature increased during all months and the mean temperature increased during nine months (Jan to March, May, July, Aug, October to Dec). The monthly average of maximum temperature was found decreased during one month (June at 5% level). The insignificant trend could be found during seven months (Feb, April, May, July-Oct.) for monthly average Tmax and during three month (April, June, Sept) for Tmean. 3.1.1.2 Seasonal average Tmax, Tmin and Tmean The result showed that insignificant decreasing tend in seasonal average maximum temperature was found during summer and monsoon season. It was increasing significantly during winter season. The seasonal average daily minimum temperature was found increased significantly during winter and summer (0.1% level) and monsoon (1%) seasons. The seasonal average of daily mean temperature was found increased during all 3 seasons. Table 2: Trend analysis of Seasonal and Annual average daily Tmax, Tmin, Tmean( o C) and solar radiation (MJ/m 2 ) for Ozat river basin. Season Mann- Kendall (Z) Conf. Level (%) Sen's Slope Slope of best fit trend Maximum Temperature( O C) Winter 1.97** 97.58 0.032 0.03 0.16 Summer 1.01NS 84.34 0.011 0.02 0.08 Monsoon -0.53NS 70.04-0.008-0.01 0.01 Annual 1.43* 92.43 0.013 0.01 0.06 Minimum Temperature( O C) Winter 2.77*** 99.72 0.033 0.03 0.21 Summer 3.25**** 99.94 0.033 0.03 0.23 Monsoon 2.51*** 99.40 0.021 0.02 0.19 Annual 3.31**** 99.95 0.027 0.03 0.32 Mean Temperature( O C) Winter 2.60*** 99.53 0.032 0.03 0.24 Summer 2.37*** 99.12 0.024 0.02 0.19 Monsoon 1.41* 92.02 0.012 0.01 0.03 Annual 2.80*** 99.74 0.024 0.02 0.25 Solar radiation(mj/sq.m) Winter 0.75NS 77.42 0.006 0.01 0.05 Summer -0.75NS 77.42-0.008-0.01 0.02 Monsoon 1.55* 93.92 0.032 0.02 0.03 Annual 0.95NS 82.93 0.009 0.01 0.04 **** = Significant at 0.1% level, *** = Significant at 1% level** = Significant at 5% level, * = Significant at 10% level 3.1.1.3 Annual Average Tmax, Tmin and Tmean It was found that the annual average of daily minimum, mean and maximum temperature was found significant increasing at 0.1%, 0.1% and 5% significant level respectively. R 2 177
Figure 1: Trend of seasonal/annual average of daily Tmax ( o C), Tmin ( o C) and Tmean ( o C) in Ozat river basin. 3.1.2 Watershed 5G1C3 3.1.2.1 Monthly average Tmax, Tmin and Tmean Out of twelve month in a year, the monthly average maximum temperature was found increased during five month i.e. Jan (10% level), Feb (10% level), March (1 % level), Nov(5% level) and Dec(5% level). The monthly average minimum temperature increased during ten months i.e. Feb(10% level), March(1 %level), April(5% level), May (1% level), June(5% level), Aug(5% level), Sept(1% level), Oct(5% level), Nov(5% level) and Dec(5% level). The monthly average mean temperature was found increased during ten month (Feb to June and Sept to Dec). However, no significant trend could be found during six months(april, May, July-Oct.) for monthly average Tmax, during two month(jan and July) for monthly average Tmin and Tmean. 178
Figure 2: Trend of monthly and seasonal/annual average of daily solar radiation (MJ/m 2 ) for Ozat river basin 3.1.2.2 Seasonal average Tmax, Tmin and Tmean The result showed that no significant decreasing tend in seasonal average maximum temperature was found during summer and monsoon season while, it was found increasing significantly trend (5% level) during winter season. The seasonal average minimum and mean temperature was found increased highly significant (0.1% level) during summer season while increased significant (1% level) during winter and monsoon season of the year. 3.1.2.3 Annual Average Tmax, Tmin and Tmean The annual average of minimum and mean temperature was found significantly increasing (0.1% level) while annual average of maximum temperature was increasing insignificantly. 3.1.3 Watershed 5G1C4 3.1.3.1 Monthly average Tmax, Tmin and Tmean Out of twelve month in a year, the monthly average maximum, minimum and mean temperature was found increased during five month i.e. Jan(5% level), Feb(5% level), March (1% level), Nov(1% level) and Dec(5% level), during nine months i.e. March(1% level), April(10% level), May(1% level), June(5% level), Aug(5% level), Sept(5% level), Oct(10% level), Nov(10% level) and Dec(5% level), and during eight month (Jan to May, Aug, Nov and Dec). However, no significant trend could be found during six months(april, May, July- Oct.) for monthly average Tmax, during three month (Jan, Feb and July) for monthly average Tmin and during four month(june, July, Sept and Oct.) for monthly average Tmean. 179
3.1.3.2 Seasonal average Tmax, Tmin and Tmean The results showed that insignificant trend was found in seasonal average maximum and mean temperature during monsoon season while, increasing significantly during winter and summer season. The seasonal average minimum temperature was found increased significantly (1% level) during all seasons. 3.1.3.3 Annual Average Tmax, Tmin and Tmean The annual average of daily minimum, maximum and mean temperature was found increasing significantly. 3.1.4 Watershed 5G1C5 3.1.4.1 Monthly average Tmax, Tmin and Tmean Out of twelve month in a year, the monthly average daily maximum was found increased during five month i.e. Jan(5% level), Feb(10% level), March(1 % level), Nov(5% level) and Dec(5% level) while minimum and mean temperature was found increased during seven months i.e. (March, May, June, Aug, Sept, Nov and Dec). The monthly average maximum temperature was found decreasing significantly during two months i.e. June and Sept(5% and 10% level). However, insignificant trend could be found during five months(april, May, July, Aug and Oct.) in monthly average Tmax, and during five month(jan, Feb, April, July and Oct.) in monthly average Tmin and Tmean. 3.1.4.2 Seasonal average Tmax, Tmin and Tmean The result showed that insignificant increasing and decreasing trend was found in seasonal average maximum temperature respectively during summer and monsoon season. However, it was found increasing significantly during winter season. The seasonal average minimum and mean temperature was found increased significantly during all three season of the year. 3.1.4.3 Annual Average Tmax, Tmin and Tmean The significant increasing trend was found for annual average minimum and mean temperature and insignificant increasing trend for annual average maximum temperature. 3.1.5 Ozat Basin 3.1.5.1 Monthly average Tmax, Tmin and Tmean Out of twelve month in a year, the monthly average of daily maximum, minimum and mean temperature was found increased during five month i.e. Jan(5% level), Feb(10% level), March(1% level), Nov(5% level), Dec(5% level), during ten months i.e. Feb (10%), March (1% level), April(5%), May(1% level), June(5% level), Aug(1% level), Sept(1% level), Oct (5% level), Nov(5% level), Dec(5% level) during seven month(jan, Feb, March, May, Aug, Nov and Dec) respectively. The monthly average maximum temperature was found decreased significantly during one month i.e. June(5% level). However, insignificant trend could be detected during six months(april, May, July- Oct.) in monthly average Tmax, during two 180
month (Jan, July) in monthly average Tmin and during five months(april, June, July, Sept. and Oct.) in monthly average Tmean. 3.1.5.2 Seasonal average Tmax, Tmin and Tmean The result showed that insignificant increasing and decreasing trend was found in seasonal average maximum temperature during summer and monsoon season respectively, while increasing significantly during winter season. The seasonal average of daily minimum and mean temperature was found increased significantly during all three seasons. 3.1.5.3 Annual Average Tmax, Tmin and Tmean The annual average of daily minimum, maximum and mean temperaturewas found increasing significantly(0.1%, 10% and 1% level) respectively in the Ozat river basin. 3.2 Solar radiation (MJ/sq. m.) 3.2.1 Watershed 5G1C2 3.2.1.1 Monthly average solar radiation (MJ/sq.m.) The result showed that the monthly average solar radiation was found significantly increasing during one month (March) only. The insignificant trend was found for the rest of the months. 3.2.1.2 Seasonal /annual averagesolar radiation (MJ/sq.m.) The insignificant increasing trend during winter and monsoon season while insignificant decreasing trend during summer season was found. The annual average solar radiation was found increasing insignificantly. 3.2.2 Watershed 5G1C3 3.2.2.1 Monthly average solar radiation(mj/sq.m.) Out of 12 months in a year, the insignificant trend could be found during nine months except month of Jan, March and April. It was found significantly increasing during two month(jan and March) and decreasing during April month only. 3.2.2.2 Seasonal /annual average solar radiation (MJ/sq.m.) Out of three seasons of the year, the insignificant increasing trend during winter season and annual and insignificant decreasing trend during summer season was found. However, the significant increasing trend was found during monsoon season. 3.2.3 Watershed 5G1C4 3.2.3.1 Monthly average solar radiation (MJ/sq.m.) It was found that the monthly average of solar radiation increased significantly during two months (Jan and March). The insignificant trend was found during rest of 10 months. 181
3.2.3.2 Seasonal/annual average solar radiation (MJ/sq.m.) Out of three seasons of the year, the insignificant increasing and decreasing trend in seasonal average solar radiation was found during winter and summer season respectively. However, the significant increasing trend was found during monsoon season. 3.2.4 Watershed 5G1C5 3.2.4.1 Monthly average solar radiation (MJ/sq.m.) The monthly average of solar radiation was found significantly increasing duringtwomonths(jan and March) only. Out of 12 Months in a year, the insignificanttrend couldbe found during ten months. 3.2.4.2 Seasonal /annual average solar radiation (MJ/sq.m.) Out of three seasons of the year, the insignificant increasing and decreasing trend in seasonal average solar radiation was found during winter and summer season respectively. However, the significant increasing trend was found during monsoon season. The annual average solar radiation was found increasing insignificantly. 3.2.5 Ozat basin 3.2.5.1 Monthly average solar radiation (MJ/sq.m.) Out of 12 months in a year, the insignificant trend in monthly average solar radiation could be found during ten months. The monthly average solar radiation was found significantly increasing during two month i.e. Jan and March. 3.2.5.2 Seasonal/annual average solar radiation (MJ/sq.m.) Out of three seasons of the year, the insignificant increasing and decreasing trend in seasonal average solar radiation was found during winter and summer season respectively. However, the significant increasing trend was detected during monsoon season. The annual average solar radiation was found insignificantly increasing for the entire river basin. 4. Conclusions The warming trend was detected in Ozat basin. However, the increasing trend of solar radiation was noticed only during monsoon season. The cereal crops like wheat may be replaced by some oilseed or pulse crop due to warming trend. Acknowledgements The authors are grateful to the Directorate of Water Management, ICAR, Bhubaneswar for the financial supports under NICRA project. 182
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