Nonstationary Extreme Value Analysis (NEVA) Software Package

The Nonstationary Extreme Value Analysis (NEVA) software package has been developed to facilitate extreme value analysis under both stationary and nonstationary assumptions. In a Bayesian approach, NEVA estimates the extreme value parameters with a Differential Evolution Markov Chain (DE-MC) approach for global optimization over the parameter space. NEVA includes posterior probability intervals (uncertainty bounds) of estimated return levels through Bayesian inference, with its inherent advantages in uncertainty quantification. The software presents the results of non-stationary extreme value analysis using various exceedance probability methods. We evaluate both stationary and non-stationary components of the package for a case study consisting of annual temperature maxima for a gridded global temperature dataset. The results show that NEVA can reliably describe extremes and their return levels.

Click Here to Read More and Download Source Code

Reference Publications:
Cheng L., AghaKouchak A., Gilleland E., Katz R.W., 2014, Non-stationary Extreme Value Analysis in a Changing Climate , Climatic Change, doi: 10.1007/s10584-014-1254-5. (pdf)

Standardized Drought Analysis Toolbox (SDAT)

SDAT can be used to generate nonparametric standardized drought indicators such as Standardized Precipitation Index (SPI), Standardized Soil Moisture Index (SSI), Standardized Runoff Index (SRI) Standardized Streamflow Index (SSFI), Standardized Relative Humidity Index (SRHI), Standardised Groundwater level Index (SGI), Standardized Surface Water Supply Index (SSWSI), Standardized Water Storage Index (SWSI).

Click Here to Read More and Download SDAT Source Code

Reference Publications:
Hao Z., AghaKouchak A., Nakhjiri N., Farahmand A., 2014, Global Integrated Drought Monitoring and Prediction System, Scientific Data, 1:140001, 1-10, doi: 10.1038/sdata.2014.1. (pdf)
Farahmand A., AghaKouchak A., 2015, A Generalized Framework for Deriving Nonparametric Standardized Drought Indicators, Advances in Water Resources, 76, 140-145, doi: 10.1016/j.advwatres.2014.11.012. (pdf)

Multivariate Standardized Drought Index (MSDI)

Multivariate Standardized Drought Index (MSDI) offers a multi-index drought monitoring framework for combining drought information from multiple variables (e.g., precipitation, soil moisture). The following code compares the parameteric and nonparametric MSDI described in the below two papers:

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Reference Publications:
Hao Z., AghaKouchak A., 2013, Multivariate Standardized Drought Index: A Parametric Multi-Index Model, Advances in Water Resources, 57, 12-18, doi: 10.1016/j.advwatres.2013.03.009. (pdf)
Hao Z., AghaKouchak A., 2014, A Nonparametric Multivariate Multi-Index Drought Monitoring Framework, Journal of Hydrometeorology, 15, 89-101, doi:10.1175/JHM-D-12-0160.1. (pdf)

Validation Toolbox Ver. 1

Performance Metrics for Evaluation of Remote Sensing Observations and Climate Model Simulations: A simple and easy to use Validation Toolbox (MATLAB source code) that can be used for validation of gridded data including satellite observations, reanalysis data, and weather and climate model simulations. In addition to the commonly used categorical indices, the toolbox includes the Volumetric Hit Index (VHI), Volumetric False Alarm Ration (VFAR), Volumetric Missed Index (VMI), and Volumetric Critical Success Index (VCSI).

Authors: Mehran A., and AghaKouchak A.

Reference Publications:
AghaKouchak A., Mehran A., 2013, Extended Contingency Table: Performance Metrics for Satellite Observations and Climate Model Simulations, Water Resources Research, 49, 7144-7149, doi:10.1002/wrcr.20498.
AghaKouchak A., Behrangi A., Sorooshian S., Hsu K., Amitai E., 2011, Evaluation of satellite-retrieved extreme precipitation rates across the Central United States, Journal of Geophysical Research, 116, D02115, doi:10.1029/2010JD014741.

Download Validation Toolbox Code and Sample Data

HBV Hydrologic Model

MATLAB source code of the modified version of the HBV hydrologic model model including automatic parameter uncertainty estimation based on the Generalized likelihood uncertainty estimation (GLUE).

Authors: Nakhjiri N., Habib E., and AghaKouchak A.

Reference Publication:
AghaKouchak A., Habib E., 2010, Application of a Conceptual Hydrologic Model in Teaching Hydrologic Processes, International Journal of Engineering Education, 26(4), 963-973.

Download HBV Matlab Code

HBV Ensemble

MATLAB source code of the HBV_Ensemble (ensemble streamflow simulation using HBV).

Authors: Nakhjiri N., Habib E., and AghaKouchak A.

Reference Publication:
AghaKouchak A., Nakhjiri N., and Habib E., 2013, An educational model for ensemble streamflow simulation and uncertainty analysis, Hydrology and Earth System Sciences, 17, 445-452, doi:10.5194/hess-17-445-2013.

Download HBV_Ensemble Matlab Code