Evaluation of the reanalysis wind over the Indian Ocean across the seasonal reversing wind pattern

75-84Present study show the similarity as well as contradictory event among the four different wind data based on monthly, seasonally and annual wind pattern over Indian Ocean. All the four reanalysis wind sources exhibit almost similar trend in their annual as well as monthly average wind pattern, however there is no strong similarity at their peak condition in space and time.The statistical analysis, based on Mean Absolute Error (MAE) and correlation coefficient (R), exhibited that the ECMWF and NCMRWF wind shows comparatively good agreement with the moored buoy data than the NCEP/NCAR and NCEP/CFSR wind under the seasonal reversing wind pattern occurs across the consecutive monsoons

A case study of coastal currents in relation with tides and winds in a tropical coastal waters of Vengurla, West Coast of India

Coastal currents consist of wind-driven, tidal, surface wave and geostrophic flows. These currents have a major role for nearshore sediment transport, but the measured data availability on coastal currents for the Indian coast is relatively less. This study analyze the variability of coastal currents along with the tides at nearshore and offshore waters during two different seasons (fag end of summer monsoon and initial stage of pre-monsoon) at Vengurla, west coast of India. Results of this study exhibited that the tides at Vengurla are mixed semi-diurnal dominated by solar constituent during summer monsoon (September to October); whereas the lunar constituents dominates during pre-monsoon (February to March). The nearshore current was dominated by the westward flow (sluggish current) during monsoon and south eastward flow during pre-monsoon, whereas the offshore flow (strong current) showed seasonality. At offshore, southerly current dominated during summer monsoon, whereas the northerly current played a major role during pre-monsoon. The current profile analysis at offshore revealed that the gradation of strong current at the surface to the sluggish nature of currents at the bottom and were comparatively higher during summer monsoon than pre-monsoon periods. This study revealed a complex pattern among winds, tides and currents at offshore

A case study of coastal currents in relation with tides and winds in a tropical coastal waters of Vengurla, West Coast of India

277-286Coastal currents consist of wind-driven, tidal, surface wave and geostrophic flows. These currents have a major role for nearshore sediment transport, but the measured data availability on coastal currents for the Indian coast is relatively less. This study analyze the variability of coastal currents along with the tides at nearshore and offshore waters during two different seasons (fag end of summer monsoon and initial stage of pre-monsoon) at Vengurla, west coast of India. Results of this study exhibited that the tides at Vengurla are mixed semi-diurnal dominated by solar constituent during summer monsoon (September to October); whereas the lunar constituents dominates during pre-monsoon (February to March). The nearshore current was dominated by the westward flow (sluggish current) during monsoon and south eastward flow during pre-monsoon, whereas the offshore flow (strong current) showed seasonality. At offshore, southerly current dominated during summer monsoon, whereas the northerly current played a major role during pre-monsoon. The current profile analysis at offshore revealed that the gradation of strong current at the surface to the sluggish nature of currents at the bottom and were comparatively higher during summer monsoon than pre-monsoon periods. This study revealed a complex pattern among winds, tides and currents at offshore

Assessment of shoreline changes along Karnataka coast, India using GIS & Remote sensing techniques

1286-1291Present analysis revealed that about 70% of the coastline was either stable or accreting in nature, whereas remaining 30% region was experiencing varying magnitude of erosion. Change rate was classified in three categories indicating the accretion, low erosion and high erosion locations. High rate of erosion was observed all along the river mouth of northern side of northern Karnataka Rivers i.e. Kalinadi, Haladi, Sharavati, Swarna etc. While the southern side of the Kalinadi River is noticed with high accretion. Erosion and accretion pattern observed along the coast is influenced mainly by the coastal process and riverine inputs. Short term analysis was also carried out along the Karnataka coast. In Karwar region, the south of Kalinadi River shows accretion during the period of 1989-2000; whereas, the same area shows erosion pattern during the period of 2000-2006. This may be due to variation in coastal processes, land runoff and geomorphologic units influencing the coast. About 168 km of coastline was found to be accreting in nature with an average rate of 1.5 m/yr followed by 71km coastal stretch with mild erosion of an average rate of 1.0 m/yr. It was also observed that the erosion was found in isolated pockets throughout the coast. The variation in river mouth morphology was quite significant. The present study demonstrates that combined use of satellite imagery and statistical method such as weighted linear regression can be a reliable method for shoreline change analysis.</span

Soil moisture estimation using RISAT-1 and SENTINEL-1 data using modified Dubois model in comparison with averaged NDVI

In past studies, several researchers took potential use of multi-temporal optical data and dual-polarized SAR data to assess drought by estimating soil moisture. In this study, Modified Dubois Model (MDM) semi-empirical model with Topp's model is used for retrieval of soil moisture. It involves retrieving the backscattering coefficient from RISAT-1 and SENTINEL-1 datasets to derive the surface roughness and soil moisture conditions. The estimated soil moisture retrieved from microwave SAR parameters is validated with field measurements provides soil moisture spatial variability over different land use classes and bare soil condition. The RISAT-1 derived soil moisture has R2 = 0.53, whereas SENTINEL-1 shows R2 = 0.84. It also confirms the possibility of two different polarization σ°HH and σ°VV backscatter involving MDM. It observes that SENTINEL-1 was found well correlated with ground-measured soil moisture. Also, the averaged NDVI sounds reliable with soil moisture ratio, which helps to understand the impact of agricultural drought monitoring

An adaptive approach to monitor the Shoreline changes in ICZM framework: A case study of Chennai coast

1266-1271<span style="font-size:11.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;letter-spacing:-.1pt;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">Shoreline change study was carried out for 25 km long stretch of Chennai coast. Landsat TM (1990), Landsat ETM+ (2000), CARTOSAT-1 (2006), Resourcesat-1 (2008) and Resourcesat-2 (2012, 2013) satellite images were used as input dataset. Field survey was also carried out using Arc-Pad GPS instrument for 2011. Three methods i.e. End Point Rate, Linear regression Rate and Weighted Linear Regression were employed to calculate shoreline change rate for <span style="font-size:11.0pt; font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-bidi-font-family:mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">1990-2013<span style="font-size:11.0pt; mso-bidi-font-size:12.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:="" "times="" roman";mso-bidi-font-family:mangal;mso-ansi-language:en-gb;="" mso-fareast-language:en-us;mso-bidi-language:hi"="" lang="EN-GB">. While, EPR method is used to calculate the short-term analysis for <span style="font-size: 11.0pt;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-bidi-font-family:mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">1990-1998 and 1999-2006. Study area was divided into four distinct zones. Totally 412 transects were generated with 50 m spacing and the length of each transects was 200 m. From the long term analysis, the high erosion was noticed on the northern side of the Thiruvottiyur region with a rate of more than 5 m/yr. Royapuram fishing harbour is noticed with an erosion rate of 4m/yr during the period of (1990–2012). 2 to 4 m/yr accretion was seen all along the marina beach. Whereas, south of marina beach, the places like Foreshore estate, Elliot beach and Thiruvanmiyur regions shows low erosion rate. From the analysis it clearly shows that the northern portion of the Chennai port is eroding and the southern portion of the port is accreting. Combined use of satellite imagery and statistical methods proves to be a reliable method for shoreline change analysis. Of all the statistical methods, WLR statistical method is found to be more reliable as it takes uncertainties and quality of datasets into account to calculate the rates of shoreline change. </span

Tsunami inundation modeling and mapping using ALTM- and CARTOSAT-derived coastal topographic data

Coastal topography is the principal variable that affects the movement of the tsunami wave on land. Therefore, land surface elevation data are critical to a tsunami model for computing extent of inundation. Elevation data from India's remote sensing satellite CARTOSAT-1 are available for the entire Indian coastline, while elevation data collected using Airborne Laser Terrain Mapper (ALTM) are only available for selected sections of the coastline. This study was carried out to evaluate the suitability of CARTOSAT-1 and ALTM elevation data sets in the tsunami inundation modeling. Two areas of the coastal Tamil Nadu that were severely affected during the December 2004 tsunami and surveyed extensively for mapping the extent of inundation were selected as the study areas. Elevation data sets from ALTM, CARTOSAT-1 and field measurement collected using Real-time Kinematic GPS (RTK-GPS) were compared for these areas. The accuracy of ALTM and CARTOSAT-1 data, the significance of interpolation methods and data used on model outputs were studied. The analysis clearly revealed that the elevation accuracy of CARTOSAT-1 data (+/−2m) was much lower than ALTM data (+/−0.6m). However, it was found that despite the differing elevation accuracy, both ALTM and CARTOSAT-1 can be used to produce tsunami inundation maps for open coasts with an accuracy of 185 m (2 grid cells) at 75% and 50% confidence level, respectively