Water Balance Modelling and Climate Change Projections for Flood Risk and Agricultural Water Stress Assessment in Bandar Lampung, Indonesia

AH. Maftuh Hafidh Zuhdi; Tandaditya Ariefandra  Airlangga; Husna Husna; Bela Ayu Pratiwi; Tyas Dwi Chintya; Syafura Azizah Wakasala; Tiara Dwi Wulandari; Muhrifki  Syaifan

doi:10.55173/agriscience.v10i1.212

Authors

AH. Maftuh Hafidh Zuhdi State Polytechnic of Lampung, Bandar Lampung, Lampung 35141, Indonesia
Tandaditya Ariefandra Airlangga State Polytechnic of Lampung, Bandar Lampung, Lampung 35141, Indonesia
Husna Husna State Polytechnic of Lampung, Bandar Lampung, Lampung 35141, Indonesia
Bela Ayu Pratiwi State Polytechnic of Lampung, Bandar Lampung, Lampung 35141, Indonesia
Tyas Dwi Chintya State Polytechnic of Lampung, Bandar Lampung, Lampung 35141, Indonesia
Syafura Azizah Wakasala Undergraduate Student Program, State Polytechnic of Lampung, Bandar Lampung, Lampung 35141, Indonesia
Tiara Dwi Wulandari Undergraduate Student Program, State Polytechnic of Lampung, Bandar Lampung, Lampung 35141, Indonesia
Muhrifki Syaifan Undergraduate Student Program, State Polytechnic of Lampung, Bandar Lampung, Lampung 35141, Indonesia

DOI:

https://doi.org/10.55173/agriscience.v10i1.212

Keywords:

Mann-Kendall, Thornthwaite–Mather, CWRSI, ENSO variability, Peri-urban agriculture

Abstract

Global climate change has intensified flood risk and crop water stress in rapidly urbanising tropical cities. This study presents a comprehensive hydroclimatological analysis of Bandar Lampung, Indonesia, using daily climate data for 2016–2025 from the ERA5 Open-Meteo reanalysis archive (3,653 observation days). Precipitation trends were analysed using the Mann-Kendall test and Sen's slope estimator, complemented by the Pettitt change-point test. Monthly water balance was modelled using the Thornthwaite–Mather method, and crop water stress was quantified via the Crop Water Requirement Satisfaction Index (CWRSI). Precipitation projections for 2026–2030 were generated using a three-method ensemble corrected with CMIP6 anomaly factors under RCP 4.5 and RCP 8.5 scenarios. Results show a mean annual precipitation of 2,472.8 ± 553.5 mm (CV = 22.4%) with no statistically significant trend (Z = 0.000; p = 1.000). The water balance revealed a net surplus period (January–July and November–December, peak January: 171.4 mm) and a net deficit period (August–October, largest monthly deficit in October: 35.8 mm). Mean dry-season CWRSI ranged from 0.753 to 0.929 under average conditions, but dropped to 0.164–0.168 during El Niño years 2019 and 2023, representing severe crop water stress with potential yield reductions of up to 20–50% for some crops. Scenario-corrected RCP 8.5 projections indicate amplification of seasonal contrasts by 2030: January precipitation rises to 422.7 mm (+40.4% versus the historical mean), intensifying flood risk, while October falls to approximately 55.1 mm, worsening agricultural water stress, with October CWRSI projected at approximately 0.40. These findings provide a quantitative basis for ENSO-informed flood early warning, adaptive crop calendars, and green-blue infrastructure planning in Bandar Lampung.

References

Aldrian, E., & Susanto, R. D. (2003). Identification of three dominant rainfall regions within Indonesia and their relationship to sea surface temperature. International Journal of Climatology, 23, 1435–1452. https://doi.org/10.1002/joc.950

Ali, M. S., Hutriani, I. W., Idris, A. W., Amanda, Z., Hetharia, B. J., & Wistoro, L. A. (2025). Evaluasi peningkatan kualitas ruang terbuka hijau kota dengan indeks hijau biru Indonesia di Kota Bandar Lampung. Jurnal Lanskap Indonesia, 17(2), 222–229. https://doi.org/10.29244/jli.v17i2.61412

Allen, R. G., Pereira, L. S., Raes, D., & Smith, M. (1998). Crop evapotranspiration: Guidelines for computing crop water requirements. FAO Irrigation and Drainage Paper No. 56. FAO.

Ariska, M., Suhadi, Supari, Irfan, M., & Iskandar, I. (2024). Annual and interannual rainfall variability in Indonesia using empirical orthogonal function (EOF) analysis and its response to ocean-atmosphere dynamics. Jurnal Ilmu Fisika, 16(2), 151–165. https://doi.org/10.25077/jif.16.2.151-165.2024

BPS Kota Bandar Lampung. (2024). Kota Bandar Lampung dalam angka 2024. Badan Pusat Statistik Kota Bandar Lampung.

Doorenbos, J., & Kassam, A. H. (1979). Yield response to water. FAO Irrigation and Drainage Paper No. 33. FAO.

Held, I. M., & Soden, B. J. (2006). Robust responses of the hydrological cycle to global warming. Journal of Climate, 19, 5686–5699. https://doi.org/10.1175/JCLI3990.1

IPCC. (2023). Climate change 2023: Synthesis report. Contribution of Working Groups I, II and III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC. https://doi.org/10.59327/IPCC/AR6-9789291691647

Kendall, M. G. (1975). Rank correlation methods (4th ed.). Charles Griffin.

Kurniadi, A., Weller, E., Min, S. K., & Seong, M. G. (2024). Future projections of extreme rainfall events in Indonesia. International Journal of Climatology, 44, 1–20. https://doi.org/10.1002/joc.8321

Mallakpour, I., & Villarini, G. (2016). A simulation study to examine the sensitivity of the Pettitt test to detect abrupt changes in mean. Hydrological Sciences Journal, 61, 245–254. https://doi.org/10.1080/02626667.2015.1008482

Mann, H. B. (1945). Nonparametric tests against trend. Econometrica, 13(3), 245–259. https://doi.org/10.2307/1907187

Muis, S., Güneralp, B., Jongman, B., Aerts, J. C. J. H., & Ward, P. J. (2016). Flood risk and adaptation strategies under climate change and urban expansion: A probabilistic analysis using global data. Science of the Total Environment, 538, 445–457. https://doi.org/10.1016/j.scitotenv.2015.08.068

Pettitt, A. N. (1979). A non-parametric approach to the change-point problem. Journal of the Royal Statistical Society: Series C (Applied Statistics), 28, 126–135. https://doi.org/10.2307/2346729

Qian, J. H., Robertson, A. W., & Moron, V. (2010). Interactions among ENSO, the monsoon, and diurnal cycle in rainfall variability over Java, Indonesia. Journal of the Atmospheric Sciences, 67, 3509–3524. https://doi.org/10.1175/2010JAS3348.1

Sen, P. K. (1968). Estimates of the regression coefficient based on Kendall's tau. Journal of the American Statistical Association, 63, 1379–1389. https://doi.org/10.1080/01621459.1968.10480934

Singhrattna, N., Rajagopalan, B., Clark, M., & Krishna Kumar, K. (2005). Seasonal forecasting of Thailand summer monsoon rainfall. International Journal of Climatology, 25, 649–664. https://doi.org/10.1002/joc.1144

Spinoni, J., Naumann, G., Carrao, H., Barbosa, P., & Vogt, J. (2015). World drought frequency, duration, and severity for 1951–2010. International Journal of Climatology, 34, 2792–2804. https://doi.org/10.1002/joc.3875

Steduto, P., Hsiao, T. C., Fereres, E., & Raes, D. (2012). Crop yield response to water. FAO Irrigation and Drainage Paper No. 66. FAO.

Sugiarti, E., & Ajrina, H. (2025). Exploring urban flooding in Indonesia: A review of drivers, consequences, and interventions. De Pamong: International Journal of Government and Civil Society, 2(1), 125–155. https://doi.org/10.71344/261g1j30

Suhadi, Khairunnisa Putri, J., Iskandar, I., & Supari. (2024). Evaluation of daily satellite and reanalysis of rainfall data over South Sumatra region. Jurnal Geomatika, 30(2), 57–66. https://doi.org/10.24895/gm.2024.30.2.57-66

Supari, T., Tangang, F., Juneng, L., & Aldrian, E. (2018). Observed changes in extreme temperature and precipitation over Indonesia. International Journal of Climatology, 38, 1751–1764. https://doi.org/10.1002/joc.5297

Thornthwaite, C. W. (1948). An approach toward a rational classification of climate. Geographical Review, 38(1), 55–94.

Thornthwaite, C. W., & Mather, J. R. (1955). The water balance. Publications in Climatology, 8(1), 1–104.

Ward, P. J., Jongman, B., Aerts, J. C. J. H., Bates, P. D., Botzen, W. J. W., Loaiza-Usuga, J. C., & Hallegatte, S. (2017). A global framework for future costs and benefits of river-flood protection in urban areas. Nature Climate Change, 7, 642–646. https://doi.org/10.1038/nclimate3350

Zuhdi, A. H. M. H., & Indarwati, L. D. (2024). Analysis of potential cropping seasons of cayenne pepper (Capsicum frutescens L.) based on water balance in Alfisol dryland, Tuban Regency, East Java, Indonesia. Journal of Tropical Crop Science, 11(1), 33–38. https://doi.org/10.29244/jtcs.11.01.33-38