Drought assessment for peri urban region : a case study of Malegaon city

Drought occurs due to less rainfall over an extended period or some time of the year, disturbing all meteorological and hydrological parameters which results in a water shortage to human being needs. The occurrence of drought in Malegaon is more frequent, affecting a large number of people in it. The unplanned water resources present around the study area, adding more in drought vulnerability impact. The topography, soil type, water demand and cropping pattern in the study area play an important role while drought monitoring in the selected study region. The demand of water for growing populations, irrigation, and industrial development has increased rapidly in the study area. The current study focus on performance of two important meteorological drought indices; SPI and RDI for 3, 6, 12 month time scale in Malegaon. The measures to cope up with frequent drought has been suggested for the present study as an outcome of research, change in cropping pattern, land use and alternative sources of water for the region has been recommended to cope up with growing water demand for the peri urban area.


Introduction
Drought is a natural disaster that happens due to lack of water availability for a certain period of time.In recent years drought disaster is becoming more severe concerning to it's post impact on people.The effect of drought can be existing for a short or long period after termination of drought [1].Drought analysis can be done using various drought indices available in literature depending upon type of drought exist in that particular region [2].All these indices are useful to quantify and monitor the drought for policy makers to identify the weather condition for a specific area [3].The impacts of drought are very composite affecting the various sectors of economy and on the human being needs [4].
Among all the indices the Standard Precipitation Index (SPI) and Reconnaissance Drought Index (RDI) has been extensively used all over the globe for the meteorological drought calculation.[5] proposed the SPI as a new metrological drought index which makes the use of precipitation data only [6].The main advantage of SPI is that using this index drought can be described on multiple time scales.[7], [8] discuss the advantage of SPI while describing SPI on multiple time scale.For any location, SPI calculation basically depends on the long-term rainfall data [9].Cancelliere et al. (2007) suggest that this index can be a supporative tool in drought monitoring and forecasting.[11] perform drought assessment and monitering using Rainfall decile (RD), SPI and Reconnaissance Drought Index (RDI).Their study results shows the good agreement in the performance of the both SPI and RDI in terms of severity of event.Tsakiris and Vangelis, (2005) proposed the RDI index which incoporate the evapotranspiration data in the analysis [12] Tsakiris et al performed drought assessment in the Mornos and Nestos basins in Greece, and their results show that RDI responds in a similar way to SPI; however, it is more sensitive and better to use it to help improve the environment [13] .Zarch et al., makes the use of SPI and RDI for the drought monitering in Iran at different time scales [14].Their study showed that both RDI and SPI give approximately similar results, and that RDI plays an important role considering evapotranspiration losses.Jamshidi et al., 2011 carry out the SPI and RDI indices at three, six and annual time scale and computed highest value of the indices and their time of occurrence [15].They concluded that the RDI index is the best suited index for a drought monitoring system for water resource planning and management.In similar way both SPI and RDI are implemented for case study of Cyprus island and their results shows that both indexes can be used effectively to assess drought condition [16].Shokoohi and Morovati studied performance of SPI and RDI in Lake Urmia Basin showing RDI index is more sensitive than SPI and concluded that 1 Corresponding author: preeti.ramkar@dypvp.edu.inRDI plays very fundamental role in drought monitoring for establishment of integrated water resource management [17].Applying both rainfall and evapotranspiration as a input parameter in drought severity calculation and monitoring, increases the validity of the results [13].
These were all about the drought assessment using SPI and RDI, concern to impact and mitigation measures of drought, Prabhakar and shaw discussed the available documentation related to the climate change of Indian subcontinent in order to assess the present preparedness and mitigation system for reducing drought risk in the country [19].The World bank (2008) mention drought impact of the years 2002 and 2003 on crop production and income in a case study of Andhra Pradesh (Chittoor and Anantapur districts), and Maharashtra (Ahmednagar and Nashik districts) [20].Udmale et al., perform questionnaire survey to trace out severity impacts of 2012 drought on domestic water supply, crop production, unskilled rural employment, and financial status of rural households in upper Bhima catchment in India [21].Asha latha K.V. et al., studied local impact of drought assessment on domestic water supply and crop production at various levels carried out in India due to climate change [22].Gupta et al., assess the strategies of drought monitoring, management of data, impacts and mitigation ways from an Indian perspective [23].
The main aim of the current study, is to observe the drought impact of peri urban scorched region considering it's land cover, soil type, water demand and cropping pattern.To achieve this, performance of SPI and RDI indices at a different month time scale were examine.The main key purpose of this work is to propose the identified mitigation measures so that future drought event impact can be minimize.

Study Area and Data Collection
Malegaon is a municipal corporation and the most populous city in the Nashik district of Maharashtra, India.The research area's map is depicted in Fig. 1.With a population of 4.71 lakh, the study area is the second largest city in the Nashik district.It is located 108.63 kilometres to Nasik's northeast.Around 330 square kilometres make up the entire study area, which is bordered by Satana and Kalvan on the west and Satana and Chalisgaon on the east.There are 76 minor villages and 155 large villages in it.It is located near the confluence of the Mausam and Girna rivers on the Mumbai-Agra National Highway (NH-3), at a height of 438 m (1437 ft), with latitude 18.42 N and longitude 77.53 E.Its headquarters are located about 280 km northeast of Mumbai, the state capital of Maharashtra.Malegaon has good connections with nearby cities like Nashik, Manmad, Mumbai, and Dhule.For the years 1981 to 2013, the research area's computed average annual rainfall and potential evapotranspiration are 520 mm and 1632.0 mm, respectively.The line map of the research area's upstream resources for water is depicted in Fig. 2. The two primary sources of water are Chankapur and Punand, while the three secondary sources are Haranbari, Kelzar, and Nagasakya.Chankapur Project and Girna Lift Projects supply the majority of the study area's drinking water.

Methodology
In the current study drought analysis and its impact assessment has been carried out using Standard Precipitation indices (SPI) and Reconnaissance Drought Index (RDI) i.e. 3month (December-February), 6-month (April-September) and12 month (October-September) for the Malegaon city using the rainfall data of 33 years (1981-2014).In addition to this the water demand, land use land cover, soil type, and cropping pattern of the study area were also studied in the present study.The detail adopted methodology is explained in the following sub section.

Standard Precipitation Index (SPI)
Mckee et al., developed the Standardized Precipitation Index [5].The Standard Precipitation Index (SPI) is a statistical tool used to measure and monitor precipitation anomalies over a specific period of time.It provides a standardized way to assess whether precipitation conditions are wetter or drier than normal for a particular location and time frame.The comparison of meteorological indices was done by Morid et al., [25].The SPI can be calculated for various time scales, such as monthly, seasonal, or annual, depending on the specific application and the characteristics of the climate in the region of interest.Shortterm SPI values (e.g., 1 to 3 months) are useful for monitoring drought conditions, while longer-term SPI values (e.g., 6 to 12 months) provide insights into longer-term precipitation patterns.The SPI is widely used in hydrology, agriculture, and climate research to assess drought and wetness conditions, identify trends, and compare precipitation patterns between different regions and time periods.It helps in understanding the departure from the expected precipitation levels and assists in water resource management, crop planning, and risk assessment related to climate variability and change SPI can be efficiently used to quantify both dry and wet periods [24].

Reconnaissance Drought Index (RDI)
Evapotranspiration and precipitation are used in the RDI computation.It determines the total deficit between evapotranspiration and precipitation.It is possible to monitor several climatic traits with RDI in an efficient manner.[25].RDI may be used successfully to track drought situations across regions with various climatic traits.[26].RDI can be standardised and normalised for calculation.Two equations are required to calculate normalised RDI.: one for initial value  0 , and another for   .They are expressed as Eqs.( 1) and ( 2): Where   is precipitation for the jth month and ith hydrological year and   is potential evapo-transpiration, and k is the total number of years of the available data.Now,   is calculated using  0 which is epressed as eq.( 2) Here  0 ̅̅̅̅ is the arithmetic mean of  0 .
Eq. ( 3) express the   Where  () is ln ( 0 () ),  ̅ is the arithmetic mean and   is the standard deviation.Comparing RDI to other indices, it simplifies its global application while also providing an accurate picture of the dry situation.The RDI and SPI acts in similar way.The Drought classification of these indices is as shown in Table 1 [27].

Water Demand
The main source of drinking water in the study area is Chankapur.This dam has been built on the Gir River at Vani in Kalwan taluka.The capacity of the dam is not enough to provide the total necessity of water of the study area.Therefore, water is lifted from the Girna Dam.
The present requirement of the study area is 50MLD out of which 20 MLD fulfilled by Chankapur dam and 30 MLD from Girna lift scheme [26].The demand for industrial water is rising at the same rate as industrial development.Due to this rise in industrial water demand, the expansion of water-intensive industries in the study region has been expanding rapidly.[27].Industries not only use water, but also pollute it.Present sanctioned requirement of industrial water is 2.17-million-meter cube from Girna but seeing the rapid growth in population and urbanization future demand up to 2030 will be 5 million meters cubic [28].
The high-water demand and large populated urban region increase the vulnerability of drought [29], [30].The unplanned structures present above the study area affect the minimum inflow in the Girna Dam, which in turns result into increased water demand.

Land cover and Soil
The land use land cover of the study area is shown in Fig. 3 for the year 2017 using supervise classification techniques.The land use land cover map shows that most of the study area is covered by built up area.Due to the increased demand for water, populated areas and agricultural areas are extremely vulnerable.Water scarcity causes crops to fail and compels people to relocate.

Fig. 3 Land use land cover map of Malegaon for the year 2017
Therefore, vulnerability to drought is measured mostly in human habitats and agricultural areas, and in few barren regions [31], [32].The soil present in study area is shown in Fig 4.
The soil present in the study area is clayey soils with moderate stoniness.This type of soils had less water holding capacity so, more vulnerable to drought.The eastern part is covered by plains.The middle part of the Daregaon hill to Lalling area is barren.The soil found is hard which creates problems in the way of cultivation of land.All the land is covered with small hills.

Cropping Patterns
The growth and expansion of power looms industry in the study area, affected in the agricultural area.Most of the study area has been turned into industrial zones.But the neighboring villages of the study area are still living on cultivation.Bajra, Jowar, and cultivation of groundnut are done during the kharif.Jowar, Wheat are cultivated during rabbi.Grapes, vegetable, onion, and sugarcane are cultivated as cash crops.In the north-west of the study area, most of the land is covered with sugarcane.Due to the abundance of this rawmaterial for sugar industry, the two sugar factories are established in Rawalgaon and Dabhadi.In the west of the study area, onion is an important crop.Besides onion, grapes and ground nuts are also cultivated on a large scale.Some of the quality onion and grapes are exported to the foreign countries.The eastern part of the study area has a small cultivation area.In this region, wherever the land is enough fertile and water is available, Jowar and Bajra are common.Table 2 shows the kharif and rabbi crops grown in the study area.

Results and Discussion
The summary of results using RDI and SPI drought analysis is discuss in this section

Drought assessment
Droughts in Malegaon are becoming more frequent events with adverse impacts on the agricultural sector, social life and on the built environment.Results show the regional SPI and RDI for the study area shows a very good correlation between the two indices.Extreme drought conditions were recorded in the years 1981-1983,2000-2002 and 2012 [20], [33], [34].

Correlation between SPI and RDI
The scatter plot of Corelation between SPI and RDI at 3, 6 and 12 time scale is as shown in figure 8.The difference of SPI and RDI increases as the time scale increases [14].The Fig. 8 and 9 shows a very good relation between RDI and SPI meteorological indices.This corelation permits the analysis of soil moisture or groundwater for short time scale and reservoir storage, stream flow for longer time scale.

Impact analysis of drought
Drought in the study region shows the both social and economical impacts.In drought period due to scarcity of water Sugarcane, Maize, onion crop fails.As a result of these farmers are committing suicides as they were not able to pay the loan.The ground water table level drops down for the year 2011-2012 in the study region because of less annual average rainfall [36].The scarcity of drinking water leads purchase of water tankers from neighbouring villages.People have to walk or move from their places to another village or city which affects on safety, health, and creates conflicts between people when there isn't enough water to go around.The Fig. 10 shows the impact of drought over a study region.

Water Resources Planning
From the current status of study area water demand is increasing day by day due to rapid urbanization, increasing population, so to mitigate this requirement, there should be linking of Gir River to the west flowing river and more stress on ground water development.

Integrated Use of Water
To cope up with drought situation there should be planning of water supply schemes, for drinking water purpose, and other demand with respective watershed as per the norms.As per the availability and demand, water supply should be calculated.Then the further water allocation should be combined and equal grid system for city & villages under study area.Study area comes under Upper Girna Subbasin which is semiarid region, hence necessary to increase the water availability from water surplus watershed to drought watershed by diverting and conserving excess water.

Crop Diversification
The deviation in temperature, climate, and rainfall in the study area recommends a combination of multiple cropping patterns.The fundamental cropping pattern for Malegaon is Bajara,Wheat, Maize, Sugarcane, and Pomegranate. (http://nashik.nic.in/htmldocs/DDMP_Nsk.pdf).
Crops like pomegranate, grapes, and sugarcane, which require a lot of water can be avoided.It is recommended to grow legumes, as they also help in restoring soil fertility and increases the chance of surviving in case of drought.Instead of Wheat, Jower is a better option for farmers to ensure an income.Farmers should be encouraged to take on more than one crop, and grow both, the cash crop and the food crop.

Conclusion
From the analysis presented in this paper, it may be concluded that both SPI and RDI can be used for drought assessment and monitoring.SPI and RDI give more realistic results.The SPI and RDI computed at 3,6-and 12-month time scales were used as an indicator of drought severity.The years 1985, 1995, 2000, 2002 and 2012 were identified as the most affected years in the study area [33], [34].Both indices can be used effectively to analyze drought conditions and possibly can be used by an expert system to predict and assess the effects of drought on various sectors.Short term analysis at 3-and 6-month scale shows that there is more seepage of water in the ground due to fractured hard sandy soil strata which requires good irrigation system and crop rotation [36].In study area where the Sugarcane, Grapes and onion are dominant crops, past crops yield history are appropriate drought indicators.Therefore, the RDI results on a shorter time scale will give valuable information of the impacts of drought on agriculture as it takes care of evapotranspiration also [37].Long period analysis at annual time scale shows the impact of drought on Gir river flow and other surface water resources so proper conservation and management system should be developed to increase recharge capacities.

Fig. 1 .
Fig.1.Study Area Daily rainfall and temperature data of Malegaon were collected from the Indian Meteorological Department (IMD) and Hydrological data user group (HDUG) Maharashtra for a period of 33 years (1981-2013).The missing data of precipitation are calculated using the Inverse Weighting Distance method.

Fig. 2 .
Fig.2.Line diagram of upstream water resources of Girna reservoir

Fig. 4
Fig. 4 Soil Present in the study area (Source: National bureau of soil survey and land use planning, Nagpur)

4. 1 . 1
SPI and RDI at 3 and 6 month (Short period) Fig.5 and 6shows the 3 and 6 month SPI Vs RDI over a study period.Short term analysis-SPI3 and RDI3 (December-February) index shows that mild to moderate drought for a short period for years 2000-04, 2007-09 and 2011-12 while 1984-86 and 2000-02 years shows severe to extreme drought.From fig.6SPI6 Vs RDI6 (April-September) s 4.1.2SPI and RDI at 12 month (Long period) Fig.7shows the SPI12 Vs RDI 12 month over a study period.In Long term analysis 12 month (October-September) are considered.From figure7it is clear that years 1983-85 and 2000-2002 were severe to extreme drought event years.The mild, wet condition was seen in the years 1987-92.The years 1994-95, 2005-06, 2009-10 were found to be very wet because of flood in Tapi basin[35].This shows that SPI and RDI index can predict accurate wet event also.The mild to moderate drought event were observed in the years 2002-05, 2007-08 and 2011-12.

Fig. 10
Fig. 10 Impact of drought in the study area

Table 1 :
Classification of SPI and RDI 2023