Dhaka, the overburdened capital city of Bangladesh, faces severe water management challenges, such as flood and waterlogging, especially during the monsoon season. The concept of a Sponge City offers a promising solution to combat these issues. This article delves into the details of the Sponge City concept, its successful implementation in other countries, and why it should be adopted in Dhaka. The Concept of Sponge City Kongjian Yu, a Chinese landscape architect and professor, pioneered the concept of the Sponge City. A Sponge City is designed to passively absorb, clean, and utilize rainwater in an eco-friendly manner by reducing polluted runoff. Essentially, it uses landscapes and infrastructure to preserve water and promote natural retention, infiltration, and purification of drainage. Key techniques associated with a Sponge City include: ·        Rainwater Harvesting: Collecting and storing rainwater for various uses. ·        Permeable Roads: Roads designed to allow water to seep through and be absorbed into the ground. ·        Terrace Gardens: Green roofs that help absorb rainwater and reduce runoff. ·        Green Spaces and Waterbodies: Parks, ponds, and lakes that act as natural water retention and purification systems. Proper implementation of these techniques can minimize the frequency and severity of floods, improve water quality, and reduce individual water usage. Green roofs, for example, enhance the quality of life by improving air quality and mitigating urban heat islands. Overall, a Sponge City can efficiently handle excess water during heavy rains and reuse it during dry periods to combat water shortages. Read more: How to Build Dhaka as a Water Wise City How China Adopted the Concept of Sponge City In 2013, the Chinese Central Government adopted Professor Kongjian Yu’s Sponge City concept, implementing it across 30 cities. Following successful trials, China aims to transform 80% of urban areas into “sponges” by 2030. The core principle of Chinese Sponge Cities is to give water enough room and time to drain into the soil rather than quickly channeling it into large dams. Instead of fast-flowing water channels, these cities employ meandering streams without concrete walls, allowing water to spread out during heavy rains. Yu asserts that replacing concrete infrastructure with natural systems can save lives. In Sponge City designs, natural waterways and permeable soils clean water and reduce pollution. Evaporated rainwater cools the city, while collected rainwater is used for irrigation, street cleaning, and other purposes, reducing the reliance on tap water. The vegetation, sediments, and microorganisms in Sponge City water systems lessen the burden on energy-intensive urban water filtration facilities. As climate change brings unpredictable rainfall, Sponge City buildings are constructed to accommodate rising water levels during floods. Compared to traditional gray infrastructure, Sponge City designs require less energy for maintenance. They reduce the load on water treatment facilities, decrease the need for air conditioning due to heat reduction effects, and use fewer resources like concrete. Additionally, vast green spaces absorb carbon dioxide and air pollutants, promote biodiversity, and provide recreational areas for residents. China has also implemented Sponge City concepts in Ningbo, a coastal city 150 km south of Shanghai. Ningbo’s sponge infrastructure includes an eco-corridor on a post-industrial site, where channeled water flows through meandering waterways surrounded by native plants. This blue space improves water quality, provides habitat for flora and fauna, and reduces the risk of waterlogging. Read more: What Can Dhaka Learn from the Smart City Singapore Application of Sponge City Model in Copenhagen Copenhagen adopted the Sponge City concept in its Cloudburst Master Plan, developed in 2012. This plan redesigns approximately 250 public spaces to retain or redirect floodwaters, including parks, playgrounds, and the Sankt Kjelds Plads roundabout. Green spaces like trees, shrubs, and soil naturally retain water and direct it to non-destructive areas.

In Dhaka and other urban areas of Bangladesh, residents often face exorbitant vegetable prices and poor-quality produce. Growing vegetables on rooftops and in yards offers a solution, providing nutritious food and saving money. The monsoon season, with its abundant rainfall and favorable temperatures, is perfect for cultivating a variety of vegetables. Let's explore ten vegetables that thrive in the monsoon season and can be easily grown in urban areas of Bangladesh. Best Vegetables for Monsoon Gardening in Bangladesh Bottle Gourd (Lau) Bottle gourd, with a growing period of 60-120 days, is ideal for the monsoon season due to its rapid growth and high-water content. It is rich in fibers, vitamins C and B, calcium, and magnesium. Bottle gourd requires a sturdy trellis for support and good drainage to prevent waterlogging. As a climbing plant, it utilizes vertical space efficiently, making it perfect for terrace gardens. Okra (Bhindi) Okra, known for its vitamins A, K1, and C, magnesium, fiber, antioxidants, and folate, takes about two months to grow and thrives in warm, humid conditions. Ideal for the monsoon season, okra can be grown in pots or directly in the soil, requiring moderate watering and well-drained soil. Read more: Delightful Recipes from Bangladeshi Kitchens to Savor on Rainy Days Spinach (Palong Shak) Spinach provides carotenoids, vitamins C and K, folic acid, iron, and calcium. It matures within 45-60 days, depending on the variety. Spinach grows quickly during the rainy season and prefers slightly shaded areas and shallow containers for cultivation. Regular harvesting of leaves encourages continuous growth, making it a reliable and nutritious addition to your monsoon garden. Cucumber (Shosha) Cucumbers are high in water content and contain vitamins K, C, and A, calcium, sodium, and iron. They help relieve dehydration and benefit skin health. Cucumbers are ready to harvest in 50-70 days after planting. Flourishing in the wet, warm monsoon weather, cucumbers need well-drained soil and plenty of sunlight. Trellising helps save space and keeps the fruit clean and healthy. Eggplant (Begun) Eggplants are nutrient-rich, providing fiber, vitamins, and minerals beneficial for overall health, including heart health. They usually take 80-90 days to grow from seed. Eggplants love warmth and can be grown in large pots or garden beds. They require regular watering and well-drained soil. The plant produces beautiful purple fruits used in various culinary dishes. Read more: Microgreens: Nutrition, Health Benefits, and How to Grow Radish (Mula) Radishes, small yet packed with nutrients, are an excellent source of vitamin C, an antioxidant that may help combat cellular damage. High in fiber but low in calories, radishes also contain CoQ10, B vitamins, calcium, and potassium. With a growing period of 55-60 days, radishes need well-drained soil and regular watering. Both the roots and leaves are edible and nutritious. Flat Beans (Sheem) Flat beans are rich in proteins, fiber, and vitamins A, K, and C. Regular consumption can help lower blood sugar levels. Flat beans take 16 to 20 weeks to reach maturity and thrive in the humid monsoon climate. They can be grown in containers or directly in the ground, needing support for climbing varieties and consistent moisture. Bitter Gourd (Korola) Despite its bitter taste, bitter gourd is celebrated as a superfood due to its numerous health benefits. It is low in calories but enriched with essential nutrients, including vitamins B1, B2, B3, C, magnesium, folic acid, zinc, phosphorus, manganese, iron, and high dietary fiber. Read more: 9 Best Indoor Water Plants That Require Minimal Care Bitter gourd thrives in the monsoon season, requiring a trellis for climbing and benefits from regular harvesting to promote more fruit production. It takes about 55-60 days from seed sowing to the first harvest. Tomato Tomatoes are a rich source of essential nutrients, including vitamins C and K, potassium, folate, and antioxidants. They thrive during the monsoon season but require protection from excessive rain to avoid fungal diseases. Growing tomatoes under a roof or using stakes for support helps maintain healthy plants and promotes fruitful yields. With a growing period of 90-110 days, tomatoes are a valuable addition to your monsoon garden. Coriander (Dhonepata) Coriander leaves are an exceptional source of vitamins A and C, offering other essential nutrients like dietary fiber, iron, manganese, calcium, vitamin K, and phosphorus. Read more: Best Air Purifying Plants to Reduce Indoor Air Pollution of Home/Office Coriander grows abundantly during the rainy season in slightly shaded areas with well-drained soil. Regular trimming stimulates bushier growth and extends the harvest period. Coriander typically matures within 40-45 days, adding ornamental beauty and nutritional value to your garden.

When the roof or terrace of a building is covered with plants such as trees, shrubs, bushes, and grass, it is termed as a roof garden. This farming practice is also known as, terrace farm, rooftop farm, rooftop garden, green roof, living roof, or eco-roof. The concept of Smart urban agriculture focuses on adequate production of crops, vegetables and fruits utilising advanced farming techniques along with IoT and AI. As Dhaka has scarcity of arable land, the methods of smart agriculture can be applied here through terrace farming. Let's take a look into the prospects of smart rooftop farming in Dhaka city. Threats to the Food System of Dhaka City Decreasing Arable Land To cope up with the increasing pressure of population, the agricultural lands are being converted to residential, commercial or industrial land uses. Such practices are reducing the scope of growing agricultural food products in different urban areas of Bangladesh including the Dhaka metropolitan city. Rising Food Inflation One of the major impacts of the Russia-Ukraine crisis was the disruption of global trades of some key foods and agricultural commodities. Like many other countries, Bangladesh has been experiencing rising prices of foods and agricultural products which is threatening the country's food security. According to BBS data, the food inflation rate in Bangladesh climbed to 12.54% in August 2023. The demands and prices of food commodities are also rocketing in Dhaka city. Read more: Inflation ticks up again as food prices remain sticky upwards Harmful Chemicals The usage of inorganic fertilisers and harmful pesticides to increase agricultural productions are making the yields hazardous for human health. Furthermore, food contamination practices such as application of harmful chemicals to ripen fruits or keep vegetables fresh for long hours are posing threat to the health of Dhaka city residents.