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All Journal JTAM (Jurnal Teori dan Aplikasi Matematika) Journal of Regional and Rural Studies
Nugroho, Salma Fitri
Unknown Affiliation
Mathematics

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A Spatiotemporal Analysis of Humidity Pattern in Bali using Space-Time Kriging with Seasonal Drift Nugroho, Salma Fitri; Fitriani, Rahma; Iriany, Atiek
JTAM (Jurnal Teori dan Aplikasi Matematika) Vol 9, No 3 (2025): July
Publisher : Universitas Muhammadiyah Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31764/jtam.v9i3.30874

Abstract

Climate plays a vital role in framing the characteristics of tourist activity. Humidity reflects the amount of moisture in the air relative to the maximum it can hold at a specific temperature, it has a direct influences on perceived comfort levels. Bali, one of the most popular destinations renowned for its breathtaking natural beauty and varied landscapes. However, this island is currently served by only four climate observation stations which are insufficient to capture the humidity across the island. Therefore, this research aims to model humidity levels in Bali based on four observed locations at 2019-2023 using the space-time kriging with seasonal drift and predict humidity at unobserved locations. This approach was choosen due to the strong seasonal pattern exhibited in climate data, which leading to non-stationary. The space-time kriging method is applied to the residuals. The most effective model identified was the exponential-exponential-Gaussian (Exp-Exp-Gau) model using a sum-metric structure. This model provided the lowest RMSE of 2.1442. Humidity contour maps suggest a gradual decline in humidity levels over time across Bali. This trend may have significant impacts for both environmental quality and the tourism sector. Lower humidity levels could lead to increased discomfort for tourists and potentially reduce the attractiveness of the destination. Theoretically, the development of the kriging model enhances the accuracy of predictions, as shows by the low RMSE. Practically, these findings emphasize the importance of integrating climate considerations into sustainable tourism planning and management strategies based on the humidity information.
Assessing Solar Energy Potential through Sunshine Hour Interpolation using Spatiotemporal Kriging with Local Drift Nugroho, Salma Fitri; Fitriani, Rahma; Iriany, Atiek
JTAM (Jurnal Teori dan Aplikasi Matematika) Vol 9, No 4 (2025): October
Publisher : Universitas Muhammadiyah Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31764/jtam.v9i4.32048

Abstract

Solar energy is a key renewable resource, particularly valuable in tropical regions like Bali, where sunlight is consistently available throughout the year. Accurate estimation of sunshine duration is essential for assessing solar energy potential, as it directly affects photovoltaic (PV) system performace and informs strategic planning for renewable energy development. This study aims to develop a spatiotemporal statistical interpolation model to estimate and predict sunshine duration patterns across Bali, thereby enhancing the planning and deployment of solar energy infrastructure. This quantitative research applies space-time kriging with local drift using sunshine duration data (in hours) collected from four meteorological stations between 2019 and 2023. The method effectively captures spatial and temporal dependencies by integrating local drift as a deterministic trend component. Among several models tested, the Gaussian-Gaussian-Gaussian (Gau-Gau-Gau) combination delivered the best performance, with an RMSE of 2.3085. The results show a clear seasonal cycle, with higher sunshine duration during the dry season (May–October) and lower values in the wet season (November–March). Northern and eastern Bali, particularly Buleleng and Karangasem, demonstrate the highest solar potential, while central mountainous areas show lower sunshine exposure due to cloud coverage. These results offer not only a methodological contribution through the application of spatiotemporal kriging with local drift, but also a practical framework for decision-makers. The insights can guide strategic placement of solar farms, optimize energy yield forecasts, and support resilient infrastructure planning in line with Bali’s climatic realities and energy needs.
The Influence of Social Capital on the Participation of Farmer Group Members in the Rice Barn Program in Pendem Village, Junrejo District, Batu City Fadhila Hasna; Ari, Ismu Rini Dwi; Nugroho, Salma Fitri; Ula, Aisyah Nabilatul; Nurrohma, Laiza Afi
Journal of Regional and Rural Studies Vol. 4 No. 1 (2026)
Publisher : Perencanaan Wilayah dan Kota FT UB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/rrs.v4i1.63

Abstract

This study examines the relationship between social capital and farmer group members' participation in the Rice Barn Program in Pendem Village, Junrejo District, Batu City, East Java, Indonesia, a community-based food security initiative encompassing irrigation management, agricultural extension, and post-harvest processing. A quantitative cross-sectional survey was conducted from January to March 2025, involving 193 farmer group members selected through accidental sampling from a population of 386. Data were collected via structured questionnaires and analyzed using Structural Equation Modeling–Partial Least Squares (SEM-PLS). Confirmatory Factor Analysis confirmed that social capital was validly represented by three dimensions, trust, social norms, and social networks, after removing two low-loading network indicators, with all constructs meeting convergent validity (AVE > 0.50) and reliability (CR > 0.70) criteria. SEM results showed that social capital was positively and significantly associated with farmer participation (β = 0.456; t = 7.319; p < 0.001), explaining 69.2% of the variance in participation (R² = 0.692). Trust emerged as the strongest contributing dimension, followed by social networks and social norms. These findings indicate that stronger social capital, particularly trust-based relationships, enhances farmer participation in village-based agricultural development programs. This study contributes empirical and methodological insights into social capital's role in participatory rural food security, including clarification on interpreting path coefficients, R², and effect size (f²) in PLS-SEM analysis.
Co-Authors Atiek Iriany Fadhila Hasna Ismu Rini Dwi Ari Nurrohma, Laiza Afi Rahma Fitriani Ula, Aisyah Nabilatul