Department of Soil Survey and Soil Conservation, Government Of
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(for official use only) Government of Kerala Report no : 1455 December 2018 SOIL HEALTH STATUS OF KERALA IN POST FLOOD SCENARIO Soil Survey Department of Soil Survey & Soil Conservation 1st Floor, Secretariat (Annexe II), Thiruvananthapuram Adv. V.S. Sunil Kumar Phone: 0471- 2333091/2335075 Hon’ble Minister for Mob :9447897700 Agriculture Fax :0471- 2333775 MESSAGE The ability of the land to feed its populace depends on soil-water-land interactions, climatic influences and how best mankind sustains productivity through interventions in mother nature. Climate in recent times has been a game changer. The flood that befell Kerala in August 2018 has resulted in destruction of natural ecosystems, soil erosion and landslides, hydrological degradation etc. According to the Kerala Government, one sixth of the total population of Kerala had been directly affected by the floods and related incidents. The flood which caused heavy loss to the agricultural sector has affected the State’s food production as well as the livelihood of lakhs of farmers. Soil degradation constitutes a serious ecological and economic problem. Soil and water must be treated as ‘economic good’ and should be managed with collective responsibility. The acceptance of interdependence of humans with the environment is recognised in the paradigm of sustainable agriculture. The department has carried out surveys in the thirteen most affected districts under very challenging circumstances and gathered very valuable data on the aftereffects of the massive deluge and accompanying landslides. For effective management of soil and land resources, we need a strong and reliable soil data base which can be obtained only from the Department of Soil Survey & Soil Conservation. I am sure that this report will serve as a reference document for the decision makers to plan and formulate programs for Rebuilding Kerala. I congratulate Department of Soil Survey & Soil Conservation for bringing out this report and wish them all success in their further pursuits. “Healthy Soils Make Healthy Crops, Healthy People and a Healthy Society.” Yours faithfully Adv. V.S. Sunil Kumar Hon’ble Minister for Agriculture ABSTRACT Department of Soil Survey & Soil Conservation conducted a random study in the 13 flood affected districts of Kerala to assess the post flood soil quality after the occurrence of “Great Kerala flood 2018”. As part of the investigation field traversing and soil sample collection were undertaken from flood/landslide affected areas. The soil analysis was carried out in the labs of the department. Though trends could not be established with respect to soil physico- chemical properties, soil acidity remains as a major problem to be tackled in the post flood scenario. More than 50% of the soils are coming under the category of extremely acidic to strongly acidic, indicating the need for urgent soil reclamation measures. Widespread deficiency of available nitrogen, available potassium, Calcium, Magnesium and Boron was noticed in the sampled locations. Deficiency of available phosphorus and zinc was also noticed in localised patches. Zinc deficiency noticed mainly in the valleys. Soil compaction, poor aggregate stability, soil textural changes etc. were noticed during field survey. Soil microbial studies were not carried out. The impact of landslide in soil profile characteristics and soil quality was also studied. Soils of the landslide area are infertile and coarse textured compared to the adjacent landscape. In majority of the landslide areas severe erosion noticed. The “A” horizon was completely lost and 50-75% of the “B” horizon lost in most of the locations studied indicating a poor regrowth of vegetation in these areas. Apart from slope, vegetation, amount of rainfall etc., soil also has a major role in making a region landslide prone in rainfall triggered landslides. Detailed investigation of soil properties especially soil physical properties need to be undertaken in the affected areas to inventorise the soils prone to the occurrence of landslides. TABLE OF CONTENTS NO CONTENT Page no 1. INTRODUCTION………………………………………………….. 1 2. BACKGROUND OF THE STUDY…………………………… 2 3. OBJECTIVES………………………………………………………… 5 4. MATERIALS AND METHODS………………………………… 5 5. RESULTS AND DISCUSSION………………………………… 11 5.1 Thiruvananthapuram district……………………………… 12 5.2 Kollam district…………………………………………………….. 20 5.3 Alappuzha district………………………………………………. 32 5.4 Pathanamthitta district……………………………………… 48 5.5 Kottayam district………………………………………………. 69 5.6 Idukki district……………………………………………………… 92 5.7 Ernakulam district………………………………………………. 121 5.8 Thrissur district…………………………………………………… 144 5.9 Palakkad district…………………………………………………. 197 5.10 Malappuram district…………………………………………… 221 5.11 Wayanad district………………………………………………… 237 5.12 Kozhikode district………………………………………………. 260 5.13 Kannur district……………………………………………………. 284 6. SALIENT FINDINGS AND INTERPRETATION………… 306 7. SUMMARY……………………………………………………….... 8. REFERENCES……………………………………………………….. Soil Health Status of Kerala in Post Flood Scenario INTRODUCTION Floods are purely environmental hazards of meteorological phenomena, but very often induced by man‟s improper utilization or abuse of the physical environment. Floods are among the most dramatic forms of interaction between man and its environment. Extreme precipitation events, landslides, and floods are the most common natural disasters that affect human society and economy (Coumou and Rahmstorf, 2012; Crozier, 2010; Hirabayashi et al., 2008; Roxy et al., 2017). Floods occur world wide, often after heavy rains in an area. Frequent extreme precipitation events cause flooding (Fowler et al., 2010), which have become common in India (Mohapatra and Singh, 2003). The frequency of great floods and extreme precipitation events has substantially increased under the Global warming scenario. India has witnessed some of the most unprecedented extreme precipitation events that caused flooding and loss of lives in the recent past. For instance, heavy rain in Mumbai in 2005, flooding in Chennai in 2015, extreme precipitation in Uttarakhand in 2013 had resulted in large flooding in the affected region with the death of more than 5000 people and claiming huge economic loss. Human losses from flooding are projected to increase by 70-80% if the global mean temperature increases above 1.5oC from the pre-industrial level (Dottori 5 et al., 2018). Moreover, Dottori et al., (2018) reported that the future flood impacts are likely to have uneven regional distribution, with the highest losses to occur in Asia. Soil degradation due to flooding is also a serious concern. Researchers from the National Bureau of Soil Survey and Land Use Planning (NBSS&LUP) and other institutes in a study conducted to assess the impact of floods on soil following the 2009 floods in North Karnataka estimated that 13 flood-hit districts lost 287 million tonnes of top soil and soil nutrients across 10.75 million hectares of farmland. A steadfast programme of recovery is needed to recuperate the condition and effect of the floods will be visible on the ground if no comprehensive scheme for recovery undertaken. In 2018, Kerala state has also witnessed a disastrous flood resulted out of continuous heavy rains adding to the list of great natural disasters of the world. 1 Dept. of Soil Survey and Soil Conservation Soil Health Status of Kerala in Post Flood Scenario 2. BACK GROUND OF THE STUDY Kerala, commonly referred to as “Gods Own Country” stretches as a narrow belt along the south-western portion of India sandwitched between Western Ghats in the east and Lakshadweep in the west. Lying between 80 18' to 120 48' north latitude and 740 52' to 770 22' east longitude, Kerala enjoys a humid tropical monsoon climate. The geographical area is 38863 sq.km accounting to 1.18% of India's total area supporting 3.4% of the national population. The average annual rainfall is 3000 mm and rainfall distribution is bimodal. Rainfall is received from both the Southwest monsoon (June to September) and the Northeast monsoon (October to December) with 60% of the rainfall being from the former. Kerala witnessed one of the biggest natural disasters that occurred in the past 100 years due to an abnormally heavy rainfall in the south west monsoon season of 2018 starting from June to August. The flood and landslides have caused devastating damage in 13 out of 14 districts of the State, claiming hundreds of lives and destroying hectares of crops, even to the extent of changing the very geographical configuration of the region. The state received 2346.6 mm of rainfall during this period as against the normal value of 1649.5 mm. Though southwest monsoon began on 1st of June in the state and continued to rain in July, a very severe spell of rainfall started from 14th August and continued till 19th August, resulting in the worst flood situation in the state since the great flood that took place in1924. It is the worst flood in Kerala after the great flood that took place in 1924. All the 13 districts of the State were placed on red alert. The Indian government had declared it a level 3 calamity, or „Calamity of severe nature‟ The heavy rainfall resulted in enormous landslides in the hilly areas and severe waterlogging in the lowland areas. The water levels in several reservoirs were almost near their maximum storage capacity due to continuous rainfall from 1st June. The intensity of the rainfall in August was so severe that, for the first time in the history of Kerala the gates of 39 out of 54 dams of Kerala were opened to release flood runoff which caused overflowing of rivers and flash flooding. Many rivers began to flow with thrice or more than their usual width, resulting in widespread flood rampant damage and catastrophe in many rural as well as urban areas of the State. 2 Dept. of Soil Survey and Soil Conservation Soil Health Status of Kerala in Post Flood Scenario Though all the 14 districts of Kerala had a share of the havoc caused by the disaster, the districts of Alappuzha, Ernakulam, Pathanamthitta, Trichur, Idukki, Kottayam, Wayanad, Kozhikode, Kannur, Palakkad and Malappuram received the major chunk of damage in terms of loss of lives, property and livelihood.