Remote sensing of optically complex inland waterbodies is challenging due to the complex nonlinear correlation between water quality parameters and water optical properties. However, integration of deep learning techniques and representative datasets offers the potential to address these challenges effectively. This study aims to develop robust deep learning models, utilizing limited but highly representative dataset of in-situ water quality and radiometrically corrected hyperspectral remote sensing reflectance (R_rs) measurements collected from optically diverse lakes of China, for independent and simultaneous retrieval of Chlorophyll-a (Chl-a), Secchi Disk Depth (SDD), and Total Suspended Solids (TSS) using Sentinel-2 analysis ready products. The GLObal Reflectance community dataset for Imaging and optical sensing of Aquatic environments (GLORIA) provides over 400 such measurements for Chinese lakes, which are simulated to Sentinel-2 R_rs with its spectral response function to build a representative dataset. Using this dataset, Multilayer Perceptron (MLP) based Deep Neural Network (DNN) models are developed and compared with eXtreme Gradient Boosting (XGB), Random Forest (RF), and Support Vector Machine (SVM) algorithms. The DNN models outperformed in effective evaluation of Chl-a (Root Mean Squared Error (RMSE) = 14.18 mg/m³), TSS (RMSE=7.23 g/m³) and SDD (RMSE=0.12 m) on test datasets and Chl-a (RMSE=14.42 mg/m³) and SDD (RMSE=0.07 m) against Sentinel-2A validation dataset of Liangzi lake. Mixed Density Network (MDN) model showed less accuracy for Chl-a (RMSE=16.76 mg/m³) on same validation dataset. Impact of different atmospheric correction processors is also assessed and DNN models achieved their accuracy on Sentinel-2 Atmospheric Correction (Sen2Cor) processor. Finally, water quality maps for various lakes in China are produced showing realistic ranges. These results show the potential of DNN models trained with limited but representative dataset in practical applications for spatial and temporal analysis of water quality.

Accurate crop yield modeling (CYM) is inherently challenging due to the complex, nonlinear, and temporally dynamic interactions of biotic and abiotic factors. Crop traits, which historically capture the cumulative effect of these factors, exhibit functional relationships critical for optimizing productivity. This underscores the necessity of multi-trait-based CYM approaches. Crop growth models enable trait dynamics with reflectance data and spectral indices as proxies for crop health and traits, respectively, to have real-time, spatially explicit monitoring. The Agricultural Production Systems sIMulator was calibrated to simulate multiple traits across the growth season based on geo-tagged wheat field ground information. Reflectance and spectral indices were processed for the geo-tagged fields across temporal observations to enable real-time, spatially explicit monitoring. Based on these parameters, this study addresses a critical gap in existing CYM frameworks by proposing a machine learning-based model that synergized multiple crop traits with reflectance and spectral indices to generate site-specific yield estimates. The performance evaluation revealed that the Long Short-Term Memory (LSTM) model achieved superior accuracy for the integrated parameters (RMSE = 250.68 kg/ha, MAE = 193.76 kg/ha, and R² = 0.84), followed by traits alone. The Random Forest model followed the LSTM model, with an RMSE = 293.56 kg/ha, MAE = 230.68 kg/ha, and R² = 0.78 for integrated parameters, and an RMSE = 291.73 kg/ha, MAE = 223.17 kg/ha, and R² = 0.78 for crop traits. The superior prediction demonstrated the dominant role of multiple crop traits with satellite-derived reflectance metrics to develop robust CYM frameworks capable of capturing intra- and inter-field yield variability.

Dissolved Oxygen (DO) is an important water quality indicator, reflecting aquatic ecological health and influencing biological and biogeochemical cycles. Remote sensing of DO is exigent yet intricate due to its weak correlation with water optical properties. This study addresses this gap by integrating deep learning (DL) techniques with Chlorophyll-a (Chl-a), temperature, and temporal features. We employed a novel indirect approach to first estimate Chl-a and temperature using in-situ time series water quality data from 94 monitoring stations across the Hong Kong coast, covering five years (2019–2023), Sentinel-2 remote sensing data and normalized cyclic month features using machine learning algorithm eXtreme Gradient Boosting (XGB) and then utilized these predicted Chl-a and temperature values, along with normalized cyclic month features, to estimate DO leveraging DL technique two-dimensional convolutional neural network (2D CNN). XGB model achieved its accuracy in estimation of Chl-a (r = 0.78, RMSE = 3.16 μg/L, MAE = 2.31 μg/L) and temperature (r = 0.96, RMSE = 1.14 °C, MAE = 0.89 °C). 2D CNN yielded a promising DO estimation accuracy (r = 0.78, RMSE = 0.67 mg/L, MAE = 0.52 mg/L). This indirect DO estimation approach achieved 50% greater accuracy than direct methods and also showed 10% improvement in r, 8%–17% reduction in RMSE-MAE values over models trained using Chl-a and temperature only, highlighting the unique potential of XGB-2D CNN approach, incorporating cyclic month features. Inclusion of cyclic month features alongside Chl-a and temperature enabled the model to capture both seasonal variations and long-term trends, significantly enhancing the predictive performance of DO estimations. Consequently, monthly/seasonal mean products of Chl-a, temperature, and DO were generated for spatio-temporal analysis for practical use.

The integration of the Crop Growth Model (CGM), Radiative Transfer Model (RTM), and Machine Learning Algorithm (MLA) for estimating crop traits represents a cutting-edge area of research. This integration requires in-depth study to address RTM limitations, particularly of similar spectral responses from multiple input combinations. This study proposes the integration of CGM and RTM for crop trait retrieval and evaluates the performance of CGM output-based RTM spectra generation for multiple crop traits estimation without biased sampling using machine learning models. Moreover, PROSAIL spectra as training against Harmonized Landsat Sentinel-2 (HLS) as testing was also compared with HLS data only as an alternative. It was found that satellite data (HLS, 80:20) not only consistently performed better, but PROSAIL (train) and HLS (test) also had satisfactory results for multiple crop traits from uniform training samples in spite of differences in simulated and real data. PROSAIL-HLS has an RMSE of 0.67 for leaf area index (LAI), 5.66 µg/cm² for chlorophyll ab (Cab), 0.0003 g/cm² for dry matter content (Cm), and 0.002 g/cm² for leaf water content (Cw) against the HLS only, with an RMSE of 0.40 for LAI, 3.28 µg/cm² for Cab, 0.0002 g/cm² for Cm, and 0.001 g/cm² for Cw. Optimized machine learning models, namely Extreme Gradient Boost (XGBoost) for LAI, Support Vector Machine (SVM) for Cab, and Random Forest (RF) for Cm and Cw, were deployed for temporal mapping of traits to be used for wheat productivity enhancement.

Desertification threatens the sustainability of dryland ecosystems, yet many existing monitoring frameworks rely on static maps, coarse spatial resolution, or lack temporal forecasting capacity. To address these limitations, this study introduces PyGEE-ST-MEDALUS, a novel spatiotemporal framework combining the full MEDALUS desertification model with deep learning (CNN, LSTM, DeepMLP) and machine learning (RF, XGBoost, SVM) techniques on the Google Earth Engine (GEE) platform. Applied across Tebessa Province, Algeria (2001–2028), the framework integrates MODIS and Sentinel-1/-2 data to compute four core indices—climatic, soil, vegetation, and land management quality—and create the Desertification Sensitivity Index (DSI). Unlike prior studies that focus on static or spatial-only MEDALUS implementations, PyGEE-ST-MEDALUS introduces scalable, time-series forecasting, yielding superior predictive performance (R² ≈ 0.96; RMSE < 0.03). Over 71% of the region was classified as having high to very high sensitivity, driven by declining vegetation and thermal stress. Comparative analysis confirms that this study advances the state-of-the-art by integrating interpretable AI, near-real-time satellite analytics, and full MEDALUS indicators into one cloud-based pipeline. These contributions make PyGEE-ST-MEDALUS a transferable, efficient decision-support tool for identifying degradation hotspots, supporting early warning systems, and enabling evidence-based land management in dryland regions.