Retrieval and validation of the Secchi disk depth values (Zsd) from the Sentinel-3/OLCI satellite data in the Persian Gulf and the Gulf of Oman.

In this study, the Secchi disk depth (Zsd) values as an indicator of seawater clarity/transparency were estimated using the ESA (European Space Agency) Sentinel-3A and Sentinel-3B OLCI (S3/OLCI) satellite data in the Persian Gulf and the Gulf of Oman (PG&GO). To do so, two procedures were evaluated including an existing methodology developed by Doron et al. (J Geophys Res: Oceans 112(C6) 2007 and (Remote Sens Environ 115:2986-3001 2011) and an empirical model proposed in this research formed by employing the blue (B4) and green (B6) bands of S3/OLCI data. In this regard, a total number of 157 field-measured Zsd values (114 training points for calibration of the models and 43 control points for accuracy assessment of them) were observed during eight research cruises conducted by the research vessel, the Persian Gulf Explorer, in the PG&OS between 2018 and 2022. The optimum methodology was then selected based on the statistical indicators including R2 (coefficient of determination), RMSE (root mean square error), and MAPE (mean absolute percentage error). However, after the indication of the optimal model, the data of all 157 observations were utilized for the calculation of unknown parameters of the model. The final results demonstrated that compared to the existing empirical model proposed by Doron et al. (J Geophys Res: Oceans 112(C6) 2007 and (Remote Sens Environ 115:2986-3001 2011), the developed model in this study which was formed based on the linear and ratio terms of B4 and B6 bands, has more efficiency in the PG&GO. Consequently, a model in form of Zsd = e1.638B4/B6-8.241B4-12.876B6+1.26 was suggested for the estimation of Zsd values from S3/OLCI in the PG&GO (R2 = 0.749, RMSE = 2.56 m, and MAPE = 22.47%). The results also showed that the annual oscillation of the Zsd values in the GO (5-18 m) is evidently higher compared with those in the PG (4-12 m) and the SH (7-10 m) regions.

Climate change: A driver of future conflicts in the Persian Gulf Region?

Ongoing global change and its direct environmental impacts, in addition to securing economic transition to the post-oil era, could trigger complex socio-economic and political crises in oil-dependent economies of the Persian Gulf Region (PGR). To evaluate the role of climate change and related policies in degrading the environment and its socio-economic impacts in the PGR, we have used a variety of available global datasets and published data. The results show that the countries of the PGR pursue some types of socio-economic reforms to alleviate the impacts of climate change. However, it seems that these attempts are not compatible with the environment's capacity. The main problem stems from the fact that political differences between the PGR nations prevent them from managing the Persian Gulf environment as an integrated natural system and consequently they have to limit their efforts within their borders, regardless of what happens in other parts of the system. The shift to alternative revenue sources by the countries needs socioeconomic preparedness while there are environmental obstacles, political tensions and geopolitical rivalries. Unless there is a cooperative approach to mitigate the effects of climate change, accompanied by a reorientation of PGR economies, the situation is likely to worsen rather than improve. To address the challenges of climate change, integrated regional collaborations are needed. Collective action, such as more investment in regional research and development and education, is required if the PGR is to successfully transition from a commodity-based to a knowledge-based economy.

Mapping of the corals around Hendorabi Island (Persian Gulf), using WorldView-2 standard imagery coupled with field observations.

High spatial resolution WorldView-2 (WV2) satellite imagery coupled with field observations have been utilized for mapping the coral reefs around Hendorabi Island in the northern Persian Gulf. In doing so, three standard multispectral bands (red, green, and blue) were selected to produce a classified map for benthic habitats. The in-situ observations were included photo-transects taken by snorkeling in water surface and manta tow technique. The satellite image has been classified using support vector machine (SVM) classifier by considering the information obtained from field measurements as both training and control points data. The results obtained from manta tow demonstrated that the mean total live hard coral coverage was 29.04% ±â€¯2.44% around the island. Massive corals poritiids (20.70%) and branching corals acroporiids (20.33%) showed higher live coral coverage compared to other corals. Moreover, the map produced from satellite image illustrated the distribution of habitats with 78.1% of overall accuracy.

Spatio-temporal variability of SST and Chlorophyll-a from MODIS data in the Persian Gulf.

Spatio-temporal variability of SST and Chl-a evaluated using MODIS products from 2002 to 2013 in the Persian Gulf. Wavelet Transform was utilized to analyze the spatio-temporal stability and abnormality of MODIS SST and Chl-a. The stationary level of SST decreases from west to the east during summer to early autumn, and increases from late autumn to spring. The stationary level of Chl-a is higher in the coastal areas, while its average ranged from 0.1 to 0.5mgm(-3). No meaningful major oscillating period observed in the abnormal variability of SST and Chl-a. The winter and summer peaks of SST and Chl-a were observed in the central parts and north-west regions. The timing of maximum SST was observed in August, which is not correlated with Chl-a maxima. The variability of SST and Chl-a in the whole Persian Gulf is seasonal, and related to river outflows, water circulation and climate regimes.

Spatio-temporal remotely sensed data for analysis of the shrinkage and shifting in the Al Hawizeh wetland.

Wetlands are regarded as one of the most important ecosystems on Earth due to various ecosystem services provided by them such as habitats for biodiversity, water purification, sequestration, and flood attenuation. The Al Hawizeh wetland in the Iran-Iraq border was selected as a study area to evaluate the changes. Maximum likelihood classification was used on the remote sensing data acquired during the period of 1985 to 2013. In this paper, five types of land use/land cover (LULC) were identified and mapped and accuracy assessment was performed. The overall accuracy and kappa coefficient for years 1985, 1998, 2002, and 2013 were 93% and 0.9, 92% and 0.89, 91% and 0.9, and 92% and 0.9, respectively. The classified images were examined with post-classification comparison (PCC) algorithm, and the LULC alterations were assessed. The results of the PCC analysis revealed that there is a drastic change in the area and size of the studied region during the period of investigation. The wetland lost ~73% of its surface area from 1985 to 2002. Meanwhile, post-2002, the wetland underwent a restoration, as a result of which, the area increased slightly and experienced an ~29% growth. Moreover, a large change was noticed at the same period in the wetland that altered ~62% into bare soil in 2002. The areal coverage of wetland of 3386 km(2) in 1985 was reduced to 925 km(2) by 2002 and restored to 1906 km(2) by the year 2013. Human activities particularly engineering projects were identified as the main reason behind the wetland degradation and LULC alterations. And, lastly, in this study, some mitigation measures and recommendations regarding the reclamation of the wetland are discussed. Based on these mitigate measures, the discharge to the wetland must be kept according to the water requirement of the wetland. Moreover, some anthropogenic activities have to be stopped in and around the wetland to protect the ecology of the wetland.